I've been sortof toying with the idea of chopping in my MY20 M3P for a MY21 one. Have had a pretty decent trade in price from Tesla (£54,000), so would cost me between £7,990 - £14,790 (depending on whether I got FSD again) to upgrade.
The only issue I've got is that my trade in estimate is valid until 15/03, and is valid for 60 days after it is confirmed. After 60 days it gets reappraised. So, assuming I ordered as late as possible - 14/03, I'd have a deadline of 13/05 to get the new car.
If the MIC M3P turned up after that date I could find myself having to fund a shortfall of however many £'s between the original appraisal and the new one, on the assumption that it would have reduced in those 2 months. Tesla confirmed to me on the phone that this 60 days is immutable - i.e. it wouldn't matter if I'd accepted an offer and placed an order, actually paying for the car and collecting it is what counts.
It sounds as if it's more likely to be mid/late May than early May, so I might be screwed if I took the gamble with the £100 non-refundable order...
Have you approached any of cash buyers like WBAC or Motorway? Or the SoR route - Simon Jones/R Symons. Of course you would need access to another car for a bit.....