how do you decide who is a racer and who is not when both have passed their test? Stopping kids and new drivers from driving fast cars would reduce potential claims, and the insurance would be cheaper.
Just because you have the money to pay for a crazy car, does not make you capable of controlling or driving the car / bike properly.
I see no reason to be added to your dad's insurance. He will not be better at teaching than a qualified instructor, and the car will be most likely be way more powerful and harder to control than the one you learn in from your lessons.