If you want a set of rules for laid back club combat, then have a look at these:

http://www.sportcombat.rcplanet.com/rules.html

If you want more strict rules with a National Points System, (and some equipment limitations that might make it tough to get club combat interested) then look at these:

http://www.rccombat.com/asp/rules/rules.htm

If nothing else, both of these have a set of written rules so you don't have to re-invent the wheel, and increase the chance that if you decide to do combat outside your club, at least you will be flying by some set of nationally recognized rules.

Good luck, and have fun!!