I'm in a similar situation and have a very, very bad credit rating (I'm 24 and just starting uni so have had a lot of time to **** up).
I applied for the coop account, got rejected. Just recently tried for Santander as well, which I'm fairly sure I will also get rejected for. I'm aware that the more you apply for, the worse your credit score becomes, so if they don't accept I'm kind of stuck.
I have a regular ultimate reward account with halifax and just rang them up explaining that I start university in just over two weeks and would like to get a student account. The bank manager refused me because I'm currently on job seekers.
I'm starting to get really worried about this now. It's not that I want an overdraft to go wild and spend money, I want it is a buffer in case I'm a little short (I do intend to get a part time job at uni). Got absolutely no idea where to turn now. The only thing I can think of, to start rebuilding my score, is to get a credit card to pay my phone bill from, then transfer the money directly from my current account. This, however, doesn't change my immediate predicament.
Feeling a bit lost :\