Ok, couple of problems here: Firstly, you have no credit history in the UK which makes you, in the eyes of the credit checking agencies "not credit worthy". That can be overcome..... Typically, a UK network will ask for a fat deposit, calculated in line with their perceived risk.

Secondly, yes you do need a UK bank account and this requires lots of checks (and more forms of ID than you can shake a stick at) and on balance, I'd have to say I'm not convinced setting up a UK bank account is worth the effort for someone who's going to be here for just a few months.

Now, the good news is that pre paid is very much an option in the UK and Europe in general (many frequent travelers have a SIM each for each country they frequently visit). It doesn't carry the stigma that seems to be attached to pre pay in the US, and rates are generally reasonable.

Also, buying an off contract phones here is easy and, if you're prepared to spend the money up front, you can have the latest and greatest of anything you like (even iPhone on pre pay from both networks that sell it). There are also some good pre paid mobile broadband options that can save you having to set up a phone line and get ADSL working.