Um, so please don't chew me out if I'm asking a stupid question. Just thought I could use some advice on this.

Well, our school band's spring concert is coming up. It's the last one of the year, and since I'm an 8th grader, I wanted it to especially go well because it's my last one at this school.

To proceed the actual concert, my teacher wanted to arrange a small jazz ensemble and told anyone who was interested to come forward. I'm a percussionist, and thinking she was just gonna put me on something simple like a tambourine or something (idunno imstupid), I volunteered. Turns out the only part is a part for the drumset, and I was the only percussionist to come forward by the deadline. Problem is, I suck at playing drumset. Well, I don't suck per say, it's just hard for me to pick up. I need a considerable amount of time of practice to be able to be somewhat decent at it.

I can't just drop out though, I don't want to piss off our band director (she scares the bloody hell out of me). But the concert is in the beginning of May, and we don't get much time to practice because the principal is a jackass who doesn't appreciate the value of the arts.

Is the drumset really that much different from playing snare drum? Any tips on comprehending the sheet music that could get me to master it faster? Really, I just need some basic tips on playing Jazz, as I never have before. Really, I've only played drumset on a basic rock version of a Christmas carol. Not much experience.

Sorry if my post is a little hard to understand. Any help is appreciated.
If you don't have a kit you can practice on regularly, try to just get some stick and play on your lap as if you're actually playing. there's a big difference so hopefully you aren't screwed too bad but just try to practice as much as possible, that's all you can really do.
what kind of jazz will you have to play?
if it's just some basic swing stuff you can get through with
swing pattern on the ride cymbal, bass drum on beats 1,2,3,4 and
snare/sidestick on 2 and 4..

so, you'd probably be best of by starting to learn this basic beat

that might be helpful:

EDIT: as I said doing the sidestick on 2 and 4 will also do the trick, you don't have to do the thing he does in the video