Not sure what your handset pricing is like over there, but last week I was in the UK and picked up a 3 network prepaid microsim for my HTC One S and it was fantastic. Unlimited data (10Gig cap according to the guy at Carphone Warehouse) 300 UK minutes and 3000 UK texts. For me, that would have been more than enough for a full month. I tethered it with my tablet and laptop for even more value. 15 pounds w/ VAT.

Coverage was decent, but I'm not familiar with the status quo in the UK. I would certainly recommend checking out the One S.