hi there. a friend of mine actualy works there and ive flown into it a few times.
manston TG Avaiation has PPL and CPL training there and there aircrafts look well kept. nice 2 mile long runway so you can bounce down it to your hearts content. pretty cool actualy when ATC ask you to hold short as you have a 747-400F on finals and ur in a little C172/worrior!!
as for quality of training i cannot say as ive not studied there. my friend however does teach CPL there and seems to know what he is talking about!!! the few people ive spoken to there seem to be quite nice but at the end of the day you will never know what you think of any school untill you have been there yourself and spoken to them, possably even done a flight. keep in mind that where ever you go, some people will have bad and some people will have good things to say.
good luck!