Wow!! I'm surprised this hasn't gotten a response yet. Must be the holiday season
When we started, we were both nervous
and shy. Our first lifestyle activity was a hotel club event. In that first evening we met a variety of people - older, younger, larger, smaller, less attractive, more attractive than us, etc., but there was one near universal. They were
friendly, and when you're new, there are going to be people who will be willing to help you get acclimated.
Ending up in a situation in which you're engaging a man who isn't turned on by you is, I suspect, not as much of a likelihood as you think it might be. There are subtle signals in conversation, body language, word choices, etc. that will tip you off quickly about whether or not there is a potential beyond polite conversation. And although you've been married since the age of 17, you've still picked up these signals over the years, even if you haven't acted on them.
If your early experiences are anything like ours were, you'll learn that you're more attractive than you believed you were.
Check out some of the forum topics on getting started. Relax. Have fun. Don't jump in with expectations. Just enjoy...