Please do not turn up to a club ride with your newly fitted cleats and pedals having never ridden on them!
Fit them ( or get a local bike shop to fit them) and practice, starting, stopping, cleating in, cleating out.
At home find a safe fence or gate to lean against, or use a turbo trainer and get all the adjustments right, and keep cleating in and out until you are much more confident than you were at the beginning!
Go for a ride round and stop at a junction or 2 (or 10) and practice the stopping/starting thing.
If you feel wobbly and unconfident a group ride is not going to improve this until you have got over the first wobble anxiety.
You could also visit cyclopark a local closed road circuit, and practice in a traffic free environment.
When you feel confident enough to ride cleats in a group, then come along to a ride and let the ride leader know its your first ride with cleats. They may ask you to ride round the car park to demonstrate that you can ride and start and stop safely, before letting you join a group.
The group is likely to help you with shouted reminders to uncleat at junctions etc, until you have got to grips with it!
Good luck, and stick with it, it’s soooo worth it.