The Best eSIM for a UK Trip

Roafly is the best-value choice in this comparison for a UK trip needing 5–20GB of mobile data. Its 30-day plans combine lower prices with access to EE, O2 and Three, giving you a useful network selection for a journey that stretches beyond central London.

The 10GB plan costs $14, and 20GB costs $20. Hotspot sharing uses your purchased allowance without a separate daily cap, so the same package can cover your phone and occasional laptop use.

Network choice deserves particular attention in Britain. EE leads the latest Ofcom performance comparison and performed strongest in its dedicated railway study. Getting that network alongside O2 and Three is one of the reasons Roafly's UK offer makes sense for a trip involving several cities.

What Does a UK eSIM Actually Cost?

The fixed-data prices below are in US dollars and cover 30 days, before discount codes. Holafly uses a different model, so its seven-day unlimited price appears in the plan column rather than under a fixed GB allowance.

Roafly has the lowest 30-day price at all three fixed-data tiers in this comparison. At 20GB, it costs $11 less than Airalo and $12 less than aloSIM, while retaining EE access and adding O2 and Three to the available network selection.

Validity matters even on a short visit. Some providers sell the same allowance with several different expiry dates; their cheapest advertised 5GB package may last only a few days. Compare the allowance and the time you have to use it together.

Roafly: 30 Days on EE, O2 and Three

Roafly's UK plans suit a journey built around several stops: London for the first few nights, a train to Edinburgh, then more time elsewhere in Britain. You can keep the same UK allowance throughout, with 4G and 5G access where available.

Choose the package around what your phone will actually do:

• 5GB: A short city stay built around maps, messages, restaurant searches and transport updates, with hotel Wi-Fi handling larger downloads.

• 10GB: A sensible starting point for a week of sightseeing, including regular browsing and social media, without hours of daily video streaming.

• 20GB: More room for a longer trip, frequent uploads, video calls or sharing data with another device.

The step from 10GB to 20GB costs $6. If you expect to tether a laptop or use your phone heavily between hotels, doubling the allowance is a useful upgrade. Someone checking directions and messages over a long weekend can keep the bill lower with 5GB.

Hotspot use is straightforward: your laptop or travel companion's phone draws from the same data allowance. There is no additional daily sharing quota. Keep large software updates and automatic cloud backups on Wi-Fi to leave more of the package for your trip.

These are prepaid, one-off purchases, and top-ups are available if you need more data. The network analysis below explains why EE is a valuable part of the package, while Three and O2 provide additional local network options.

EE, O2 and Three: What Changes on Your Trip?

Britain's mobile networks do not perform identically. The differences become especially relevant on trains, around rural accommodation and when moving between England, Scotland and Wales.

EE earns its place on a rail itinerary

Ofcom's June 2026 railway research examined 24 segments of major lines across England, Scotland and Wales. EE met its good-performance benchmark on 42% of the railway segments measured, compared with 21% for Three and 20% for O2. The benchmark combined connection speeds and responsiveness suitable for tasks such as video calls and streaming.

That is a strong reason to prioritise EE access when choosing an eSIM for a trip with intercity trains. Roafly includes it at every allowance in the table, so you can choose the amount of data you need without moving to a more expensive provider just to get EE.

Save rail tickets and essential directions before boarding. The same study shows why a train journey is a poor place to depend on an uninterrupted connection for an important meeting, even with the strongest-performing network.

Three and O2 give you additional options

The broader picture also favours EE. Ofcom's 2026 Mobile Matters report, using data collected from August 2025 to July 2026, recorded good connection-performance scores of 85% for EE, 82% for Three and 77% for O2.

Three finished close to EE on that measure, making it a useful part of Roafly's network selection. O2's results varied more between UK nations: its score was 65% in Wales and 80% in Northern Ireland. EE scored 82% in both. These figures describe connection performance in covered areas, rather than the proportion of the country with a signal.

EE's lead is particularly relevant if your itinerary includes Wales. Roafly includes that network alongside Three and O2, so the purchase gives you both a strong starting choice and additional supported networks to use during the trip.

Local accounts add some practical detail. In a Scottish mobile-network discussion, one resident described better reception in central Edinburgh and West Fife after moving from O2 and Three to a service using EE. That experience gives a specific example of why the underlying network can matter during a Scotland visit.

Heading farther into the countryside? Use the postcode of your accommodation in Ofcom's Map Your Mobile tool and compare EE, O2 and Three, including the indoor view. This is more useful for a rural overnight stop than checking only the nearest city. Download the area map before leaving Wi-Fi, especially when your route continues into the Highlands or rural Wales.

The Tube has its own coverage pattern

London's underground connectivity has improved considerably, but coverage still follows individual stations and tunnel sections. TfL's current mobile coverage information includes the whole Elizabeth line, plus sections of the other Tube lines.

On the Jubilee line, for example, mobile coverage is available through the stations and tunnels between Westminster and Canning Town. Other parts of the Underground have different gaps. Check the lines you will actually use instead of assuming every Tube journey has continuous data.

Both 4G and 5G are used in the rollout, and no special app is needed to connect to the mobile signal. Station Wi-Fi is a separate service with its own access arrangements; the cellular coverage map is the relevant reference when planning to use your eSIM.

How the Other UK eSIMs Compare

Airalo

Airalo identifies EE as the primary network for its UK fixed-data offer. Its familiar app may be convenient if you already use it for other trips, but EE access is also included with Roafly at lower prices across the matched 30-day tiers.

The practical distinction here is value. You do not need to pay Airalo's higher fixed-data prices to get an eSIM that supports EE in the UK.

Saily

Saily's UK fixed-data plans cover the same 5GB, 10GB and 20GB allowances and allow hotspot use without a separate sharing restriction. Its setup centres on the app, with activation on arrival once the eSIM and roaming settings are enabled.

Roafly costs less at all three 30-day tiers and gives you named network options to assess against your itinerary. That is useful if your buying decision includes rail travel or a rural stay, rather than just the allowance shown in the app.

Roamless

Roamless offers a different reason to consider it: alongside fixed packages, it has a pay-as-you-go model whose unused credit does not expire. That can appeal if you make occasional short trips and prefer to keep a balance for later.

The prices in the table are its 30-day fixed-data plans, rather than pay-as-you-go rates. Those UK plans use Vodafone, O2 and Three. Roafly's combination includes EE and costs less at the compared allowances, making it the stronger fit for the UK data purchase covered here.

aloSIM

aloSIM supports EE and Three, with several package durations. Its 5GB seven-day option costs $8.50, while the 30-day version in the table costs $13. That shorter package is worth distinguishing from a like-for-like monthly comparison.

Roafly's 5GB plan costs $9.90 for 30 days and includes O2 alongside EE and Three. It gives you more time to use the allowance for a small increase over aloSIM's week-long option, and costs less than aloSIM's matching 30-day plan.

Holafly

Holafly charges by trip length for unlimited phone data. Network fair-use policies can temporarily reduce speeds, and its UK plan allows 1GB of hotspot sharing per day.

That sharing limit deserves attention if a laptop is part of your trip. An unlimited allowance on your phone does not provide unlimited tethering. Roafly lets you use your purchased allowance across your phone and hotspot without a separate daily cap, which is a more flexible arrangement for occasional heavier sharing.

Setting Up Your eSIM for the UK

Install before departure while you have a reliable internet connection. With Roafly, the UK plan's validity starts when the eSIM first connects to a supported network in the United Kingdom, so installation outside the UK can be done ahead of the flight.

1. Check compatibility and carrier lock. Your phone must support eSIM and be unlocked for use with other providers. On an iPhone, the carrier-lock information is under Settings → General → About.

2. Add the eSIM using Roafly's instructions. Scan the supplied QR code through the phone's add-eSIM menu, or enter the supplied installation details manually. Keep the email accessible on another screen if that makes scanning easier.

3. Name the line clearly. A label such as “Roafly UK” helps you distinguish it from your home SIM when changing data settings.

4. Select Roafly for mobile data when you arrive. Turn on the eSIM line and enable data roaming for that line. Keep data roaming off on your home SIM and disable automatic data switching if your phone offers it.

5. Check the connection before leaving the airport or hotel. Turn Wi-Fi off briefly and open a webpage using mobile data. If it does not load, confirm that Roafly is the selected data line and that its roaming setting is on, then briefly toggle airplane mode or restart the phone. Use the APN details supplied for your eSIM if setup instructions require them.

On iPhone, these controls sit under Cellular or Mobile Service; Android menu names vary by manufacturer. Follow the instructions for your device rather than copying settings from another provider's eSIM. Keeping your home line enabled for calls or texts remains subject to your home carrier's roaming charges.

Heathrow has free airport Wi-Fi if you need to retrieve the installation email or finish setup after landing. If you prefer to buy on arrival, compare the options for SIM cards at Heathrow before deciding between an airport purchase and an eSIM.

Hotel Wi-Fi can handle backups and large downloads during the trip. If you are weighing it against home-network roaming or a local SIM, the guide to how to get internet in the UK explains those alternatives.

Questions Before You Buy a UK eSIM

Will one eSIM work in London, Edinburgh, Cardiff and Belfast?

Yes. Roafly's UK plan covers the United Kingdom, including England, Scotland, Wales and Northern Ireland. You can use the same package when travelling between those cities, without buying a new country plan at each stop. Your data allowance and validity continue across the trip.

Does a UK eSIM also cover the Republic of Ireland or France?

Roafly's UK country plan covers the UK. Belfast is included because it is in Northern Ireland; Dublin is in the Republic of Ireland and needs separate coverage. The same applies when taking Eurostar from London to Paris. Choose country plans or a regional package that explicitly includes every destination on your route.

Will my eSIM work on the London Underground?

Yes, on sections with mobile coverage. The Elizabeth line has coverage throughout, while other Tube lines have their own connected stations and tunnel sections. Your eSIM uses the available mobile network normally; a station Wi-Fi sign alone does not tell you whether the next tunnel has cellular coverage.

Which network should I look for on a UK rail trip?

Prioritise EE access. It performed strongest in Ofcom's dedicated railway research, making it a useful network to have when your itinerary includes intercity trains. Roafly supports EE alongside O2 and Three. Keep tickets downloaded so a temporary loss of signal does not hold up a ticket check or your arrival plans.

Is 10GB enough for a week in the UK?

10GB is a sensible starting allowance for a week of maps, transport searches, messaging, browsing and some social media. Regular video streaming, large uploads and laptop tethering increase consumption considerably. Choose 20GB if those are part of your plans, and use hotel Wi-Fi for backups and software updates.

Does Roafly include a UK phone number for calls and texts?

Roafly's UK plans provide mobile data, without a local phone number. Your existing WhatsApp account continues to work over the data connection. If you need traditional calls or a UK number for SMS, compare UK SIM cards with calls and texts before buying.

Roafly's 10GB plan is a sensible starting point for a week in the UK; 20GB is the better buy when you expect to share data or stay longer. Choose your allowance from the UK eSIM plans and install before departure. Both options include EE, O2 and Three, with 30 days to use your data.