I'm 21, not sure if that constitutes a mature student but I was in a similar situation recently. I'm doing an MA at Kings next year. I know its going to be a lot of hard work, so I really didn't want to be ending up in a flat full of freshers. No offence to them, but its just not what I want at this stage. Anyway, I've accepted a place in some private halls where all the rooms are self contained studios. I've been to view quite a few of these in London, and on almost every occasion the person showing me round said that they were popular with mature students and postgrads. It appealed to me because they all had common rooms and social events so I won't be completely isolated, but when I need to get on with work I'll hopefully be able to get some peace and quiet.