I'm going on holiday to the UK for just a week and then Paris for a few days. I'd like to get prepaid sims for both countries that include data. While looking around, I've seen some places allow me to buy pay as I go sim plans. I'm not sure though if I'll need to wait until I get there because it doesn't seem to let a US address buy them/sign up. What is the best option for me as I don't wish to pay AT&T's outrageous data rates. Even the World Traveler plan is pitiful when compared to some of the local sim data rates. Thanks!