I too have experience of Cambridge Helicopters; mainly the experience that I gained my PPL(H) there. There is a definate advantage in having loads of uncontrolled airspace within 2 minutes flying time and the full ATC (and highly flexible) facility certainly makes things easier for the student. It is also helpful having the space of an airport with a fraction of the traffic.
I can't speak highly enough of the instructional staff who on many occasions went out of their way to asisst me during my training there.
Their ab initio training is done on R22 as you might imagine although they also have R44 available and B206. They now handle the training requirements for Aeromega at Stapleford so not much point looking although I am unaware if anyone else trains down there.