Please help!

Since this might be your final chance, u should confess. If u continue to hold it, then at some point u will regret not telling him.

That depends on who this 'crush' is. If it's a friend u will most likely see them out of school as well, so if so would u rather take it meer slowly?
However if this person is not your friend (or someone u hang out with normally) try and get a little closer to them first, see how they react with u spending time with each other, and then ask them to the movies, of for a drink.
Once you're comfortable in their presence i say go for it. Just tell them u really like them, and hope the feeling is mutual. If not it doesn't matter, ask that u remain vrienden instead, that way his/her feelings may grow on u perhaps?
It's entirely your decision, if u feel that your chance will be missed if u don't do it now, then do so. If u feel u will continue to see them away from school etc and u feel like u have some time, get the words in your head straight first.
Either way i wish u luck :)

If in the future u would be able to see him then I would tell him if not I would let it slide.

ok well if u dont want to have sad what if then do it. If u really like them all u can do is give it a shot. fallow ur hart-, hart not ur head. if they say no atleast u tryd and wont say what if i did ask? we onley get one shot at things most of the time now is urs r u gonna take it of leave it. now onley u can answer that?