whoa back there speedy, its easier to open the popes drawers than a bank account in the uk. if you can open one before you leave home then do it, or enquire through HSBC about their special deal for non uk residents. to open a uk bank account you need a proof of address, ie a power bill, phone or gas bill, the snag comes when these items require you to have a bank account in the first place. see the nasty cycle? a hostel address will not be sufficient to open an account. it is much easier to have an account already there than try to open it afterwards. so many friends of mine had difficulties and then had the hassle of cashing cheques, losing money on transaction fees and extortionate cashing fees. the banking system in the UK is still very outdated so dont expect them to be up with the play on a lot of things. They have only just introduced using debit cards into the shops and supermarkets 5 years ago.
when and if you are successful getting your account open it takes time before they give you a debit card and a lot longer to get one you can use overseas in europe. and god forbid if you go over drawn.
mind you if its just for saving then make sure you try and get the best deals on bank fees, do a comparison between barclays, lloyds and nat west.