For self funding/sponsered students, there is also BAE at Cwmbran, they are about to unveil their secret weapon in the form of the new aerodrome simulator, which really is the dogs bollocks and light years ahead of anything available at NATS or ASTAC.
That said, to date, ASTAC and Bae Cwmbran are probably on a par with pass rates and the only thing you have to remember about NATS is that the instructors make a huge deal of being under immense pressure
and, whereas at the two private institutions, the instructors will bend over backwards to help you, at Bournmouth, fail to make the grade within the prescribed limits, and you are toast.