If you have the US paperwork (title document) showing its date of registration, then they will give you a J, K, L, M or N plate. The chassis number gives the date of manufacture, and the Lotus Europa Registry will tell you when it was first invoiced.
http://www.lotus-europa.com/regspcl.htmlI got AOA96M for 4129R which is a Jan 74 registered car built in Oct 73.
You need to send the import duty paid paperwork. You would have paid this to clear customs when you picked the car up from the docks (Felixstowe or Southampton?)
When I registered 4129R, I had to get an MOT and pay road tax at the same time, but now 40+ year old cars are exempt. But they may want it inspected to MOT standard.
You will need to send insurance details. The insurers will insure it on the chassis number as it has no registration number.
I have 6 more to register, so let me know how you get on, and if anything has changed.
I am in Edgware Mon-Thursday just down the road from you, so if you need anything, let me know.
I have converted 7 from LHD to RHD so I know all the grubby details of what to do, or what you have done.
Alex in Norfolk (weekends)