Liz there is a Krispy Kreme in Canary Wharf Shopping Centre at 30 Canada Place!!
as for Tim Hortons, I like them First tried them in Toronto and there is one that Jacqui and I Terrorise visit in Portland ME when I'm in town, with a very tolerant staff that come out of the kitchen enmass to see these to crazy Brits Laughing in the window seats (we seem to laugh a lot when we visit together)