Earlier quoted context omitted.
I can't use the Co-op. They won't let me have an account because I apparently have a bad credit rating. (The real reason, I expect, is because I have no credit rating as I've never applied for a credit card or loan, or been late on a bill.) They're probably overdue a computer system overhaul as they've recently taken over several other banks and building societies, notably the Britannia where I had a few friends work…
It's worth having a credit card just for the cushion it gives you in exactly these kind of circumstances tbh.
Just make sure you pay off the balance in full each month so you never get stung by interest.