If you're going to be in the UK/EU frequently, it might actually be worth looking into getting a contract phone. I got a great deal from Vodafone a few months ago with 1200 local minutes, 500 minutes a month to the US/Canada/EU, unlimited texts, 750MB of UK data, and 20MB a day of data anywhere in Europe for £35 a month on a 24-month contract. They also threw in a free unlocked Samsung Galaxy S II, worth about £350 retail! ^
Set it up for online statements and direct debit and you'll be good to go. Saves me a ton of hassle and money every time I'm in Europe or the EU as intra-Europe roaming rates are very reasonable and data/messaging is free.