I can't comment on OAT or Bristol - but I found CATS excellent and have not heard anyone there say anything bad.
I would suggest you try and make the time to pop into all the schools you are considering (preferably when one of the residential weeks for the distance learners is on) and see what the atmosphere is like / what the students say.
As for CATS take a look at:
http://www.cranfieldaviation.co.uk/ and see what you think. Give Stuart Smith a call as well - his enthusiasm for learning is really motivating.
Whoever you pick - enjoy.
OC619
P.S. To be pedantic I did the CPL distance as opposed to ATPL.
P.P.S. If EGLD is an indication of where you are then CATS is certainly accessible (sp?).