We're flying into Heathrow but don't really need to bother with a SIM there in the airport necessarily. I was thinking somewhere around the Waterloo station would be good, and the website states "Shops & services: for all you need - Heel bar, key cutting, bureau de change, clothes, stationery, florists, photo processing and mobile phone store". But when I look at the store descriptions, I can't tell which is a mobile phone store. Anybody know? Am I missing something?
And on that note, is it simple enough to pick up a SIM that will work in both London & Paris? Since we don't speak French, I'm thinking the same card for both places would be easier, but I don't know how feasible that actually is.