Don't worry so much about what you don't have with you. Try to just focus on what you have at hand, and making the most of it.
Try to use existing structures, like posts, fences, trees, whatever, as supports when you shoot. You can easily shoot the XP2 at 1,000 and get great results.
Does it look better at 200? Yes. But that's not something you can use at this event anyway, so don't worry about what's out of your control. It just adds confusion.
Focus on staying relaxed, for steady hands, good focus, and good framing. With the lenses you have you should be able to shoot in pretty dark conditions.
I hope it turns out all right for you, and that you have a fantastic time at this event, which seems very important to you.