First question, Is your car finished and ready for its test?
If so then be quick and you may be able to get it SVA'd
You need to download the SVA1 form ( I don't have the link but someone will add it i'm sure)
Then you need to send it off along with pictures of your build ( This is to prove you have built it)
Also you need to send off all the receipts of the parts for the car, along with a receipt for your donor car.
And a cheque for £190 i beleive it is.
As for the VIN number, this idealy should be 17 caracters long and stamped onto the chassis.
Hops this is helpfull
I'm in Angouleme 16 where are you?