Cabair............No!
There are two very good clubs in your area that I could recomend, The BAFC at Wycombe or WLAC at White Waltham. the BAFC would be at the top of my list.
I don,t know The Pilot Centre a Denham so I cant comment on them however comments above seem to be favourable.
As for Cabair they seem to get most of there business from "new starts" who are totaly new to aviation, this way they can make a lot of money from add on charges and the poor victim ...... sorry student has not got the nouse to know that other clubs don,t charge for such things.
Make a quick phone call to BAFC or WLAC and ask what the TOTAL cost of an hours instructional flight is............. then ask the same question of Cabair, make sure that you get the whole answer there will be a base price + instructor time + landing fees+ VAT.
You will soon see that the BAFC price will seem more expensive at first however once the Cabair "add on,s" are taken into account you will find the BAFC or WLAC to be the best deal.
I have left quality of instruction and aircraft maintenance standards out of this post as I don't have time to open that can of worms.