Just phoned Tesla (for the first time!) and spoke to a friendly and helpful chap after a very short wait.
Anyway, he said my M3P is on a boat which is due to arrive in Zeebrugge on 24/03 and the UK a day or two after that, so delivery hopefully at the very end of the month or early April.
Any suggestions for which boat I'm looking at? Thanks.
Nope.