If your car has broken down and can’t be repaired in time, your only option is to ask your driving instructor, a parent or a family member if you can use theirs, so long as you’re insured to drive it.
If you can’t find an alternative car that meets the requirements, you’ll have to cancel your test and rebook for another time.
This is why it’s crucial to think about the reliability of your car if you plan to take your driving test in it.