hello back to basics
it could leave uk in a steel container with an invoice for whatever value you fancy ... it`s then up to you to present the invoice and pay the relevant tax / duty at whatever rate import duty is ??
to give you an idea on transport costs i bought a car from fort scott, ks loaded it in a 40 ft cotainer, trucked it to kansas city and railroaded it to virginia and then shipped to southampton uk. door to port was about $3000 for the transport in a 40 ft container ( should be a similar price going the other way ? )