I had a locker where I could store most of my work clothing and shoes, and left my cycling gear in there during the day. If you don’t have a locker, you’ll have to find some way to transport your day cloths, a rack or panniers would probably be best.

This has the advantage that if it’s raining, you don’t have to wear wet clothes all day.

If changing isn’t an option, then you should avoid clothing made from natural fibres, such as cotton, as these will absorb the sweat, and will cause odour during the day. Man made fibres will allow the sweat to wick through and evaporate, so you’ll be drier, although the deodorant will still be a good idea.

Incidentally, if you have front suspension that you can lock, this will help while you’re cycling on the roads.

Freshen up when you get to school. You might be able to hit the gym shower as well.

Get a good pair of padded mtn. baggy shorts and wicking top. Take a change of clothes with you in a pack, or store a set in your locker(s), or in a basket on a rear rack. My daughters have a rear rack with a stainless steel basket attached. They can throw in their books, lunches, soccer bags right in the back. You could do the same and have room enough for a change of clothes too.

Soccerref