I'm moving to Manchester next month,and the real estate agent I'm dealing with won't lease to me without work unless I'm prepared to pay for a 6 month lease upfront,which I will be doing.
Another thing,it's quite difficult to open up a UK account just by walking into a bank branch. I'm an HSBC client,and I opened up a UK HSBC account from my home country.The transaction cost $200 for whatever reason,but my account is open with funds in it and that's peace of mind and one less thing I have to do once in the UK.The catch 22 is that most landlords/agencies won't rent to you without a UK account,but you need a UK residential address in order to open a UK bank account.
My advice to you is,open a UK account BEFORE coming over,I'd strongly advise AGAINST trying to do it after moving.