Hi t(AD)pole,
Yes there is a lot of pet stuff at Croydon - since they are the biggest part of the membership BUT your 'trick' can be a retrieve, speak on command etc ie an 'obedience' trick & there is nothing stopping you from training your dog to YOUR standards - & you can organise to be assessed so you don't have to go through all of Basic.
I train at Croydon, sometimes train at Sherbrooke and do agility at K9Agility at KCC park on Thursday nights - all good positive clubs. Whatever club you go to - be prepared to explain (nicely!) to an instructor if you have a problem with something that goes against your beliefs. And remember, even in a 'positive' club there will be variation amongst instructors. Good luck!
Dot