I have included a link to FSA - Money made clear website which shows various forms of ID you can use for opening an account. Your Passport will be the main one but for proving an address you may have to speak to staff at a bank branch. At the end of option 3 on this web page link is a Publication link, where you can view a guide entitled "proving your identity", this may help also.
http://www.moneymadeclear.fsa.gov.uk/products/bank_accounts/opening_an_account.html
I don't know if you have already done this but you should also fill in a P86 Form and send it off to the HMRC to let them know you are back in town, A reply letter from HMRC can also sometimes help prove your address depending on which bank you use for opening an account.
On the credit card, you may find it a bit harder than it was years ago to open a credit card account as banks have really tightened up on lending criteria. I don't know if they are offered in the UK but a "secured credit card" helped start off my credit history in the USA when I was there last year. Again ask at the Bank branches you visit, I put a Grand up front for security and that was also my credit limit for the first 18 months after which a standard credit card would be issued.