I think our university newpaper had an interesting article a few weeks back. According to it, beginning this year if you rent out a flat from a landlord as a student, you can demand that the deposit be held (i.e. the landlord has to pay it to) the council to watch over it.
Quite a good scheme IMO as last year I've had problems with a landlord who ended up not wanting to pay back the deposit even though nothing was broken saying this year's flat suggestion he only made so he could keep our old deposit as "concession" which of course is both illegal and nonsensical. After a few months of tug-o-war and threatening legal action and getting the university office involved, he finally paid back. So yes, get a trustworthy landlord and make sure everything is covered in your contract. If there's something unclear but the landlord verbally tells you that something you ask about is included, have him add it to the contract in writing because he can later argue it was not included.
And general rule of course is to take inventory of the flat when you move in, take dated pictures to prove any obvious problems and less obvious problems such as plumbing, leaks etc.

Good luck with your flat in any case. I am still looking for one for next academic year.