Thanks everyone some great comments from all!
+1 for "forums show the worst of everything"
Gareth, I was feeling the same concern leading up to my M3 delivery based on other experiences here. But actually I was pleased to be prepared and to know what to look for. Yes, there are some horror stories, but the vast majority are fine or have minor issues which are easily fixed. It is annoying that Tesla expect customers to spot these issues rather than picking them up in QA, but knowing that just made me check more carefully than I otherwise would have done.
For me, when my car arrived earlier this month it wasn't perfect, but it wasn't terrible. And I was prepared. My issues were easily rectified and the service I received from West Drayton was actually very good. They couldn't have been more helpful. On delivery day evening I got a service centre appointment through the app for the next working day, phoned ahead in the morning and requested a loaner, got a Model X for 4 days. Took it to IKEA
My kids thought I had the Batmobile, and I got to try FSD with NOA for a while.
Of course I would have preferred a perfect vehicle, but my experience overall was within expectations.
My only niggle was 4 days felt like a long time for a faulty left repeater (camera) and a couple of paint issues (one was a tiny defect and the other was a scuff that polished out) and it would have been nice if they had stuck my car back on a supercharger after the work. But overall I am happy, the car is well worth it.
FWIW I am 20 mins from Heathrow. I can appreciate if I wasn't close it would have been a lot worse.