hi there.... u could contact the Kennel Club and they can send you a list of registered clubs in your area.
If u have found then a trainer of ur choice u should ask of his/hers qualifications and experience as there are plenty of self so called trainers out there not having much clue.

Im not sure if u also look into training the dog or only socialising but I would suggest to look for an outdoor training class with indoor facilities incase the weather is bad
Indoor is not bad too but only if the numbers arent too high.
I find to train the dog outside alot better and relaxed and thats where the dog has to listen and indoors there is just too much noise, barking, ppl talking, trainer explaining and so on.

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