I did my PPL at Compton Abbas last year. They switch you between instructors a bit at first, but I'm told that's normal and it certainly doesn't matter much at the start of the course - in fact it's quite beneficial. Once you get on to the meat of the course you'll probably have almost exclusively the same instructor.
I never had a lesson cancelled due to unavailability of an instructor or aeroplane, only because of weather. I passed my skills test with the minimum hours, and I can thoroughly recommend doing a PPL there.
Feel free to PM me!