My strategy for larger rides like chairty rides, can apply to your situation. Go slow and careful for the first few miles. At the start, there really is one pack, but after a couple of miles it will break apart. When it does you can find your own pace, find other riders at your own pace, and enjoy your ride. But don't assume anything about the competence or safety of other riders at the start. And be careful yourself not to do anything too unpredictable as there are inexperienced rider behind you too.
Don't be afraid to go slow, most people get caught up at the start, go out too fast, and hurt for the last part of the ride. Better to get to the half way mark, and increase your pace than to blow out too early.
My first group ride in many years this spring, I went with a group who had all trained all winter and rode a lot in the early spring. I lead them for a while, but on the return leg, had some challenges with a hill. One of them stayed behind to pace me back to the group. Cyclists tend to be friendly and encouraging.