The deposit protection scheme is there for a reason. They can make reasonable deductions from this but if you think that they are charging unfairly, you have redress.
I should have said that when you take photos make sure that they are date stamped and also e-mail them for further evidence of the date.
The worry you have is not the keeping of the deposit, but the issue of them perhaps suggesting that, because you have 'breached the contract', that you have forced them to terminate this and that somehow this makes to liable for the remaining rent (ie six months). Naturally, this is a crock, but this is why I think you should see a solicitor.
The problem is that even if they might want to evict you, in the current climate they probably can't afford to risk having the place empty. And this is something you need to remember. It's a renter's market. They need you more than you need them.
Vicky