As Tim says, just get yourself a ticket and get along, whether alone or with friends. The paintballing community is one of the friendliest around and you'll meet a lot of new people that will make you feel completely welcome.
You'll find our team, the Renegade Rebels, in attendance at most games throughout the year so feel free to find us and come along and chat anytime. All of our lads are friendly guys and we're always happy to help new players and introduce you to some of the other regular faces that will be about.
Everybody has been the new guy to these type of events so we all know what it's like. Any anxiety will disappear after your first few minutes amongst like minded players.
If you post up what area you're from you'll probably find there will be people willing to help out with recommendations for local sites and even sharing transport to the bigger UK scenario games.
You don't need to be in a team to play these events but you'll often find that somone will take you under their wing and let you run alongside them to make you feel at ease.
Welcome to paintball. It's a great way to spend your free time.