Forgot you have a saff already. Yeah, if you can get the work done then mybe look for a saff that is generally good but needs a freshen up at thr right money. I personally wouldn't do the look-a-like lump change option, get the real thing.
That way you will end up with a nice saff around hopefully the time you turn 21 and can get it insured at a reasonable price.
Make sure you read up on classic policies, as they can be a great option, but the age of the car is a factor, so see what the cut of point is, ie don't by a G plate and realise F is the latest they class as claissic.