Experiencing a similar problem myself at the moment! Maybe you could send an email or call one of the organisors of the munches, and ask if they would mind meeting you one-to-one first or something as you're new to this all and are a bit worried about turning up alone first time. I'm sure it's not that unusual for people to request such a thing as it must be quite daunting for a lot of people to just turn up alone first time! Let us know how it goes :-)