A decent trainer will give you ideas and things to work on so that your dog starts to focus on you and stops going nuts when he sees a roomful of other dogs

A decent trainer will encourage you and make you feel as if you CAN do it and if you stick with it you'll find you and your dog improve gradually - sometimes you'll find improvements come in leaps and bounds!

I started off in puppy classes and when we moved on to a Competitive Obedience class all my dog wanted to do for the first couple of sessions was sniff the floor

I almost gave up there and then, since all the other dogs (much older and more experienced, granted) were doing heelwork, sendaways, retrieve, scent... and there was me with my littlun who was beside herself at seeing all these Collies and completely incapable of taking any notice of me

But within a couple of weeks she had learned that the other dogs were NOT for playing with and things just got better and better

Maybe ring first, ensure that the trainer uses kind, humane, positive methods (body swerve anyone who uses choke chains/punitive methods of training) and then go for it!! I guarantee the trainer will have seen dogs like yours a thousand times and everyone else will be too busy with their own dogs to worry about what yours is doing