Horses for courses
Gloucester is a nicer area. Cwmbran a bit too close to Swansea.
I have heard that some people have had issues with one of the (Chief?) instructors at Gloucester - but I think he does the APS courses.
Not sure which is the better student accommodation - perhaps a visit to both (possible in a single day - they are very close to each other.)
Worth the trouble if your boss is willing to spend the money. Both will get you through the course if you put the work in I think.