jumbliee is the best, but roughly a bit expensive.
I would recommend self-catered, because i am sure you won't like english food at all. also, it would much much cheaper if you buy things to cook for yourself. a good news is you can easily purchase the materials just stepping out of the door, there is mini-market around a roundabout at the left hand side. 2 mins walk distance!!:)
i would strongly recommend you take your own laptop, that would make a big sense!! you can also bring it to use in library. library in Jumbilee is the most beautiful one.