How to Buy a SIM Card in London in 2026

London is the easiest city in Europe to buy a SIM card in, and the easiest to overpay in. The airports and the Eurostar terminal sell them at a premium, Oxford Street has every network's shop within a few hundred metres, and the supermarket by your hotel has a starter pack by the till. This guide is the city version: where to buy between landing and checking in, what it costs, how the Tube behaves, and the eSIM you can install before you leave home. Our UK plans are on the UK eSIM page.

Arriving: Heathrow, Gatwick, Stansted and St Pancras

Heathrow has SIM vending machines dotted through the terminals and EE sells its tourist packs at Heathrow and Gatwick; Stansted and Luton have counters in arrivals. All of them charge more than the same pack in town, which is the price of being connected before the train. St Pancras, where the Eurostar arrives, has no SIM counter of its own, but the phone shops around the station and along Euston Road sell starter packs, and King's Cross next door has a supermarket. If you arrive late at night, the vending machines and supermarkets are what is open.

Shops in town

• Network shops. EE, O2, Vodafone and Three all have stores on Oxford Street and Tottenham Court Road, and in the Westfield centres at Stratford and White City. Staff fit the SIM and check the phone.
• Supermarkets and newsagents. Tesco and Sainsbury's sell starter packs for Tesco Mobile and giffgaff; corner shops carry Lebara and Lycamobile, which are the cheapest per gigabyte and good for calling abroad.
• Online before you travel. giffgaff and the networks post SIMs to UK addresses; an eSIM avoids the post.

What a London SIM costs

A 30-day bundle on any network is about £10 to £15 for 10 to 20GB with unlimited UK calls and texts; tourist plans with 25GB start from about £20. Lebara and Lycamobile undercut that for data and include international minutes. The SIM itself is free or a pound or two. There is no registration and no ID check for a prepaid SIM, and no credit check.

The Tube, the museums and day trips

Mobile signal now reaches much of the Underground, so maps and messages work on most of the central lines and stations, with gaps on the older deep lines. Every station has free Wi-Fi for ticket-holders, and the big museums have free Wi-Fi inside. Day trips are where the choice matters: Oxford, Cambridge and Brighton are covered by all four networks, but a Eurostar day in Paris needs either EU roaming, which Three includes on most bundles and the others charge for, or a plan that covers both countries. For that, the Europe 25GB eSIM at $19 covers the UK and 31 other countries for 30 days.

Install before you land

With an eSIM phone you can skip every counter above. Our Three UK 25GB eSIM is $17.27 for 25GB in the UK plus 6GB of roaming, unlimited UK calls and texts, a UK +44 Three number, 5G and hotspot, valid 30 days with no identity check. Our EE 30GB eSIM is $15.27 a month on a 30-day rolling plan, with 30GB in the UK, 2GB of EU roaming, unlimited UK calls, 50 UK texts, 10 international minutes and Wi-Fi calling. Both run on the real networks, so the Tube and the day trips behave exactly as they would on a shop-bought SIM. For a trip that goes on from London to the rest of Europe or to the USA, the Vodafone Travel eSIM is $26.60 for 25GB in 76 countries with unlimited local calls and a UK number.

Side by side

Our recommendation

For a London break of a few days to a month, install the Three UK 25GB eSIM or the EE 30GB eSIM before you leave and go straight from the plane to the Elizabeth line. If a Paris day is part of the plan, add the Europe 25GB eSIM or pick a Three bundle. Buy a plastic SIM in a supermarket, not at the airport, and only if your phone cannot take an eSIM. Set-up steps are in our eSIM installation guide, and the full range is on the UK eSIM page.