I just saw this, and since your event is not until July, I thought I throw in my .02
You can't become an event photographer in one gig, so I would just use your camera with the kit lens. Rent or borrow a Canon flash for the weekend and shoot on P or green box unless you are more advanced than that. The Canon flash has a focus assist beam to help you in low light as long as you shoot in the "one shot" autofocus mode. If you are not familiar with processing software, then shoot jpg's, not raw. Finally, if you bounce your flash, make sure the walls are a neutral color that will not throw a color cast on your subjects. Shooting in jpg mode makes it difficult to change the subjects back to the color that they really are 
Good luck and keep everything within your ability. Otherwise you will be struggling at the computer afterward and cursing yourself for ever taking on the project.
