Have flown out of Billins on and off for 5 years have. Always friendly, the kettle is usually hot for free tea and biscuits. Very relaxed informal, head honcho last seen taking a skills test in shorts and a tee-shirt, it was a very hot day. Prices are about average for Cranfield, but they do have an interesting assortment of aircraft you can have a go in, c152,172 and cardinal RG, Cherokee 6 300ph for touring and a Seneca for those that like two engines.
Have also done stuff with Bonus and Cabair, from commercial necessity. Both of these operations are more formal and commercial, while Billins is more club like.
Best thing is to visit and you can go to all the cranfield schools at the same time and draw your own conclusions.
cheers
H-B-H