I need some help with taking pics inside of a circus tent!

I have a XSi with the kit lens (18-55mm). I'm taking my son to the Ringling Bros. circus in a few weeks and I want to bring my camera. Of course flash photography isn't allowed. I'm still learning how to use the settings but it would be GREAT if someone could give me a suggestion as to what setting might be the best for that environment (dark with spotlights etc). Use the CP filter or not? THANKS in advance!!

Definitely don't use your Circular Polarizer inside the tent.

Do not use your CP... A CP costs you light and you won't have much to begin with.

About the best you can hope for is to crank up your ISO, shoot wide open and look for either static subjects or find creative ways to use and show movement.

If it's at all possible, please get a telephoto lens. If you have to shoot at f/5.6 please let it be at 200-300mm instead of 55mm, which doesn't cover a great distance at all. Unless you have the VIP seats, but even then, I'm sure that's still fairly far away from the action.