I already posted, but I have to say it again- GO!! Yes, it might be stepping far out of your "comfort" zone, but don't give in to your fear. There is no way your school is going to just send you off to China unprepared. The issue with not speaking the language is really much less significant than you may think. I am telling you, most people in Asia speak English (certainly any that are involved in a school program like this would). I have been all over Asia and lived in Thailand for a short time (right outside of Bangkok). It was very rare for me to encounter a person that didn't speak almost fluent English. English is even referred to as the unifying language of Asia.
Really, when I lived there, I did not even consciously think sometimes that I was in Asia. English television stations like CNN are available there. I lived within a couple blocks of McDonald's and Pizza Hut (not to mention numerous shopping malls, grocery stores, etc...that were pretty much identical to what we have here). I certainly never, ever felt unsafe. Keep in mind, this was also without the help of a school. Your situation, I'm sure, will be even more structured and protected. They are not just going to put you on a plane to China and leave you to fend for yourself. Go for it!