QMUL accommodation v ScapeWatch
Privacy-wise, QM halls are super-private. The cleaner only has access to the shared kitchen (and bathroom if you're in cheaper halls) in the mornings, and no one checks your room on a regular basis. Every now and then you'll get an email to tell you they are checking the in-room fridges, or the carpets, etc. but you are left alone for the most part.
Campus is relatively safe, and I'd assume Scape would be pretty much the same. The most annoying thing about QM halls is the constant threat that the fire alarm will go off at 2/3 am, which it often does if people are smoking, etc. A lot of people at QM live in Scape, so there are plenty of social opportunities. Most of these people only live in Scape if they were rejected for halls on campus, though.
QM halls, overall, are pretty good for student digs, to be honest. Try to get accommodation on campus if you can, because it will round off your first year experience.