Hi! I don't go to QUB currently but I'm also from SE England looking at Belfast and I went to visit the city and on a tour of the campus a few weeks ago. The best way to describe the city would be like a mix of York, Edinburgh and Liverpool- it's small and easy to get around but not so small to be boring. The campus is kind of at one end of the city, a 20 min walk or so from city centre but there are buses constantly. The campus is easy to get around - the main building is really pretty and not too far (15 mins) from the main undergrad accom. Student Union was big and really nice, they have a lot going on. I wasn't able to go into accom but saw the main social building, called 'treehouse' which was really nice, where washing machines etc are.
Good luck!