LTV and Leo have the right idea. A good TBRPG GM is equally strict and loose with his storyline. It's perfectly alright to stage battles and have a story you want followed, but you have to remember that these are other people's characters playing. They're going to do stuff you can't predict, and sometimes, they'll break things they shouldn't.
In all seriousness though there are enough RPG vets here on the boards that if you can get a good one (And I mean a good one, not just your regular guy who posts a ton) they'll both be more than willing to help you, and will do a really good job helping you cope with the random stuff players can pull off.