http://www.russellgroup.ac.uk/
How important is this?
Re: the russell group:
Not very unless you want to pay three as much for the exact same degree qualification and experience you can get at any other good non-russell university for three times less.
Look at the info and stats for the course you want to study. If its medicine, even somewhere like east anglia metropolitan will do. For other courses like english, aim for oxbridge no less.