I currently live in the US but will be going to London for six (6) weeks. I have an iPhone 4 on ATT. I'll probably use the phone to call/text friends/family, with occasional data usage to check email, web browsing, maps, etc. I will have wifi access at the place I'll be living at. What do you recommend I do (Use ATT's International Roaming, buy a new SIM card, etc.)?