I think you'll be fine for a first game. Make sure you adhere to the loadout of the Rhino Corps team, most people have the stuff hanging in their closets already.
The biggest difference I think you'll notice is the field - I'm assuming that you've been playing smaller games in a yard or very small field - well, this field is ENORMOUS, and fairly difficult to maneuver through. There are no indoor areas of this field for CQB.
I'd stick with the MP5, if I were you.