Quick story; 12 yrs old, playing clarinet for a year, probably the worst player in the band. When I learned the school was buying a baritone sax, I begged to play it. I guess they figured they had nothing to lose so they did. It wasn't long before I was the section leader of the saxes and going to all-state band. I have played sax ever since, 62 years, mostly a tenor player but since 1998 I have had a baritone - I got the alto in 1983 and the soprano in 1998 too.
'not good enough'; you'll find the baritone parts in school band swing between playing bass parts with the low brass and being a part of the sax section. It doesn't take much skill to play the 'oom-pahs' with the sousaphones and a sax part is a sax part. It might take a little more air and of course the horn gets heavy in a parade, but if you are of average size you should be able to do it.
School baritones usually get beat up. When you try it, there could be many reasons that you might have trouble with it, from leaks, damage or even a damaged mouthpiece. If this is the case, you'll have to get them to authorize repairs so you'll have a legitimate shot at making it work.