I don't see it as expensive, but then again this coming from someone who's lived in the centre of London most of his life! It can be as expensive or as cheap as you like. Rents can vary for a house anywhere from £40pw - £100+pw depending what you're after.
Because Nottingham has such a large student population, lots of bars, clubs, restaurants etc will have offers on nights of the week to entice students in! For example, 241 on meals, cheap drinks offers etc etc. So if you shop around then you could get a really good deal. Of course, if you want to go to a classy venue every night you can, but it's going to cost!
I know people that can easily live of £30-40pw. Personally, for me it's about £60-80pw plus £65pw rent. But like I said, different people will choose to manage money differently.