I've never heard of insurance for having the car parked up.
If it's that expensive to insure, why not just try for a classic car (limited milage) policy, that way it's covered when on your driveway.
I assume you just want it covered incase some pikey comes along and decides to have some fun.
How long do you intend keeping it on the drive? If it's only for a short while, you could get it added as a second car to your parents policy, so that it doesn't cost them much extra. But that won't really help you if you're trying to build up a NCB.