Avoid high roaming cost when you travel to Europe and buy a UK sim card for traveling in Europe when you arrive at London Heathrow! It is the best way to stay connected and it doesn’t have to cost much. In this guide for buying a sim card at London Heathrow I tell you where to buy a UK sim card, show you the best 5G network and tell you all the available options regardless which terminal you arrive at Heathrow Airport.