I'm planning a business trip to London for a month and was wondering if anyone has brought their hobby phone overseas with them. Any tips or tricks? I'm going to have a lot of time on my hands so I'm sure at some point I'm going to get that itch. Any help would be appreciated. Thanks.

are specific to one system.  Your best bet is to pickup a phone in UK.  http://www.tripadvisor.com/ShowTopic-g186338-i17-k3489239-Buying_a_disposable_cell_phone_upon_arrival_in_U_K-London_England.html