+1 on showing up for a ride and giving it a try. There are a ton of rides in Austin, some very social that would be good for you. I think Mellow Johnny's has a ride that is just a cruise around sort. It doesn't sound like that is what you are looking for, but it's a good idea to get comfortable riding with others before even thinking about doing it at any speed. It's also a good chance to talk to others about what other ride options there are (talk to the ride leaders).

Also, you are a beginner, sorry. I rode a bit when I was young and have been back on the bike for almost 2 years and over 10k miles. I am still very much a beginner/maybe intermediate in comparison to the people I ride with. Ask for advice and listen/watch the people with experience (even though they can sometimes be cold). Group cycling can be a little hard for newbies to get into unless you have a thick skin. Remember that everyone is basically trusting each other with their lives to some extent, so we take it seriously. Nothing makes people more nervous than a beginner that doesn't think they are a beginner.