Oh, you'll have a BLAST! Just keep in mind that in lessons, you usually switch off partners. That's a good thing. It helps you learn better. I'm less into ballroom than I am into Lindy Hop, but the principles of dance are the same. Listen to the instructor, pay attention to your partner, and look out for the other couples on the floor. But, most importantly, SMILE AND HAVE FUN! ^_^
The people in the dance communities (save those few that pop up in every group) are wonderful. I feel very safe and welcome among other dancers. I can contact dancers I don't really know in another city and they're more than willing to put me up for a couple of nights and show me around and take me out dancing with them.
I've met amazing people through dancing and had wonderful experiences. It helped me grow from a shy, self-conscious person into a more confident and socially secure person. Heck, I would once freeze up at the thought of going up in front of a room of people to read something, let alone *gasp* talking to a boy. Now, I've performed in front of hundreds and I have no trouble asking a guy to dance.
If you don't like one form of dance, don't give up completely. Think of the types of music that appeal to you. If you like swing jazz, jump blues and the like, perhaps you may want to try Lindy Hop. If you like groovy blues, there's always Blues dancing. Argentine Tango is a very intense and sensual (and I don't mean in a naughty way) dance. If you like latin music, there's the more relaxed Salsa scene.
Make sure you practice on your own a little. Get out on the dance floor with people who are better than you. It's the only way you'll learn. I think I learned just as much ON the dance floor as off it. Laugh off the mistakes and just keep moving. So that you'll feel a little more comfortable in the dance environment, try looking over this:
http://www.utdallas.edu/~aria/dance/etiquette.html
That's all for now. ^_^ Have fun!