Hmmm, there are a few workarounds here, one is to do everything in the box, that is use VSTs of pianos etc. but plonking out MIDI notes for a pianist aint no fun at all.
Do you have a MIDI keyboard, it would at least enable you to practice with cans on, make some progress towards getting your album ready to track, and then you might not need so long.
Even if the rehearsal room were empty you'd have to spend quite a while getting the mics placed just right, (mic'ing up a Grand can be quite fiddly)
Anyway, not much help really, let me know what you manage to sort out...Which Uni is it? and what are you reading?
Best of luck with your results...
Another way is to get the musicians that are in the rehearsal room to practice your album, unlikely but worth a punt, or join a society that might make this possible.