I'm returning back to Uni for something entirely different (if all goes to plan) and as far as I know all I've lost besides a few weeks rent and (potentially, not 100% sure how it works) 1 years student finance funding is time.
It's not as major as stressy people who value their schooling over their mental wellbeing would have you believe, honestly.
EDIT: If you are in halls, make sure you contact someone about the policy for rent. Some Uni's make you pay a full year and if you leave, well, too bad.
Some make you pay by installments, others are full year with refunds to the leaving week, etc.
If you chose a place that makes you pay the full year and doesn't refund you might be pretty ****ed unless your fam can pay for it.