jmiller - As a private seller,
generally "Caveat Emptor" applies ("Let the buyer beware").
https://en.wikipedia.org/wiki/Caveat_emptor
"Sold as seen" also works if you are a private seller, but not always if you are a Trade Seller.
( Where the "Sale of goods act" also has some influence. )
Again,
generally you would only have a problem in court if you lied about the condition of the car.
So if you said it was 100% safe and it turned out it wasn't, you
might have a problem.
But if you are honest in describing it as a home build car with no guarantees of quality then you
should be OK.
Note: I am an accountant by trade, not a lawyer, so WTF do I know?
Good luck, Paul.
PS
Welcome to the forum.
