I think you should, the fact that you wanted to go in the first place means you're really excited about helping out there. And after all, it'll only be for two weeks, that's nothing, imagine how those people need to live and survive there, I'm sure it can't be as bad as you fear.
By the way, this is a huge opportunity, you'll carry it with you all your life, the memories to it, and the fact that you'll be helping people out there so much, that's worth alot more, than wanting to stay spotlessly clean for that time, and fearing not being it. =P
Go for it!