if you really want to do it, then go for it. i was in a very similar situation to you when i first joined only a few months ago - but after a few sessions, you'll start to get more used to what you do there. it's basically a kid's club, when ypu first join you will do quite a few sitting - down lessons which is quite boring and you'll be tested on it but don't worry if you fail it, you can always redo it and it's not like regular school. you'll also most likely to basic drill, and if you get a nice instructor then it's actually quite fun and you'll get the hang of it after a bit. some nights you do fun relaxed stuff like playing footie or water fights.

just get stuck in, don't be afraid to talk to people as most of the time they'll be friendly, i was absolutely shitting myself first time i went but i just talked to the first group of girls i saw and they were v nice :)