Tbh mate your prob best off building your no claims and waiting til 21.
I know what your gonna say to that, the same i said to my mum when she said that lol, but seriously paying that much for insurance is madness, not to mention the power of the car for an inexperienced driver, no disrespect.
I waited and ok i am 25 in june but getting quotes for £400 fully comp on VR6 but only got 2 years NCB and 9 points, (well 3 points on licence but got 6 points 4 years ago so are no on licence)
Thats obviously my view and not my money! lol
Good luck though