while you can use tor & it's possible to set a country specific endpoint (so you appear to have a UK ip address), I'd be surprised if you'd get sufficient throughput to stream iPlayer.

what I do is to run openProxy on my UK PC and ssh into it when abroad - that way, I get a d/l speed at the foreign location which is nore or less as fast as my UK broadband upload speed - more than enough to watch iPlayer.