You can leave up to award of wings with no notice and only repay the costs of the uniform issued to you. Once wings are awarded there is a return of service commitment which used to be five years, but may now be different.
My advice would be to ring the ACLO in the morning, and ask them to get onto it. It's partly their problem, and they should be able to help you sort it out.
The first year will be the worst, and there really is very little time off, even at weekends, though you will get block leave, roughly in line with school holidays, probably two weeks at Christmas and Easter, and three in the summer if you have a summer leave while still at BRNC. There will also be block leave or something like it at the flying training establishments.