So when they say matched im presuming this means Tesla receive the order and ship the vehicle but without telling the customer until it’s arrived in the UK ?
Yup, that's about the top and bottom of it. As others have said Tesla have dramatically reduced the number of options to streamline production and so that they can make for "stock". Generally your best bet is to phone and ask what they have lying around (if you are flexible on colour etc.) because if they have something suitable "in stock" it avoids the wait, but I don't know if that fits well with using Leasing. Probably works better on the continent where they can aggregate all left-hand-drive cars for all countries. For example, to maximise convert-to-cash in the last few days of the quarter they erected a tent on the docks in Holland and shipped cars to anyone local who could collect - pretty much "straight off the boat"... I can't find the article but a figure of 600 cars a day sticks in my mind.
I guess Leasing should be fine, finance-wise, but I've typically had only 48 hours to pay-and-collect by the time paperwork is resolved (probably compounded when V5 needs to be in name of company and it wasn't all straight from the get go at their end). The amount of manual messing around they do with invoices / credit note must cost them a fortune.
Heathrow is probably worst for MS / MX handover. They can shift 100 - 200 cars a day there, and only a few are non-M3. I picked up an MS there in November and they were a bit apologetic that all they had was the group PowerPoint presentation for M3 ... mine was a replacement for existing MS so not a problem for me, but I'm not sure that is the right approach for punters shelling out £100K for the first time! and for sure the M3 layout is not the same as MS / MX. But there are staff on hand, so if I had needed some help I am sure they would have made time for me.
I expect that MS / MX handover at any of the other, smaller throughput, sites would be much more personal.
Tesla have reliance on the hassle of purchase soon being forgotten once customers get the pedal-to-the-metal ...
Luxury!