I'm pretty sure you don't need to pay it back, from asking a few people at my uni. Might be different in yours though. Noticed your thread was in Jan - did you quit? How did it go?

I just had a nightmare with my flat and ended up paying 6 months rent up front. They weren't happy with the fact that I was classed as a student, despite my stipend and wanted a million references from various people. I had to use my mum as a guarantor, who couldn't pass the reference as they wanted 6 months of her accounts up to date from a chartered accountant. As her accounts weren't up to date (and she didn't want to have to sort them out just for this) we had to pay it all up front, which I think is pretty stupid. Its a small studenty area and I'm sure most people don't have that sort of cash lying around! grrrrrrrr