Have you any ISA's? Maximum is �3000 but its tax free and instant access. Other instant access routes will pay poor interest, I would be tempted with the isa and then fix term your remainder in a 90 day account.
I've got an account with ING Direct, they're pretty good and I have no problems. The only possible downside is if you don't like computers, because it's done on-line. What I like is that you can see how much interest you've earned there on the screen in front of you - with my ISA I had to wait 12 months for the bnk to write to me. I'm not sure what the interest rate is at the moment, but that may be worth checking out.