Depends on how much your deposit was, and at the end of the day, that is what a deposit is for - to protect against a buyer pulling out.
I think a reasonable outcome would be to cover the cost of the repair within reason, or any costs the dealer has incurred as a result of you saying you'll take the car, plus maybe another 15% because they'll feel they've been messed about.
Sorry to hear your circumstances have changed, hopefully you'll get in a zed soon enough.