If my dad adds me as an additional driver to his car and I crash it, does he lose his no claims bonus?

If the accident was your fault, then your dad would lose his no claims discount. How much no claims discount he will lose depends on how much he has at the moment. If the accident was not your fault, then he won't lose anything. This is assuming that your dad is the policyholder and you'll be a named driver on his car insurance policy.

OK, what if me and my dad agreed to not repair the car, then the insurance company won't remove my dad's no claims right?

Unfortunately it doesn't work out this way. If you have an accident, you are required to tell your insurers and when you inform them, a record of the accident will be held on file for you. This means that renewal quote will be calculated with less no claims discount.

If you decide not to inform your insurer and they later find out you haven't disclose this information to them, your insurance will become void.

Thanks for that. Guess I must buy my own insurance as I want to collect NCB as well and also don't want my dad to lose his many years of discounts.

Any car you recommend for cheap insurance?