It may have changed but when I was in the UAS (8 years ago) the flight training given was in line with the basic flying syllabus for the RAF, i.e that given to zero hours pilots who join the RAF full time. How far you progress through that training depends on how often you attend and how much you are willing to get involved and participate as a squadron member. They expect very high levels of commitment.
They also expect students to have a genuine interest in joining the RAF full time once you complete university, although there is no formal commitment required (unless you are sponsored through university).
The flying is not recognised if you want to put the hours towards a PPL as the syllabus is taught by serving RAF pilots, not civilian instructors, and therefore they have no civilian qualifications. Therefore if you were thinking of using it as a way of starting to build time in order to gain a CPL i'm afraid you may be disappointed.
That aside though it's great fun and better than your average university society. And it's free!
Hope that helps...