Thanks for the replies.
The work was carried out by Chelsea Coachworks near Battersea Heliport. I emailed some photos of the damage, they asked for one more of the whole rear of the car, and I got an email quote back for £350 + VAT.
I had another quote from a garage I've used in the past but it was higher and more vague as to the final price, so I opted to go with the cheaper quote. My brother had some work done by them last year and he was happy with their work, so I wasn't taking a massive gamble.
Like some other Tesla owners, I was worried that the bodyshop didn't have much experience of aluminium repairs but they responded by saying that many of the cars they work on have aluminium including JLR cars, and they do lots of repairs for high end main dealers in the area. In fact the place was cluttered with newish Range Rovers and a Rolls Royce.
I took the car in on Monday morning and it was ready for collection on Wednesday afternoon. I very pleased with the results. The paint match is excellent, and you cannot see that a repair has been carried out (as expected). My car is ceramic coated but they don't use the type of ceramic that was previously applied and theirs are much higher gloss than mine. So they suggested returning to the original detailer to have the same compound re-applied to the whole rear quarter.
If you are looking for a repair, I would suggest contacting them if they are close enough to you as I found the whole process simple and the quality of the work very good. BTW,I haven't been paid for this feedback nor did I receive any discount for posting this.
Sorry about the qualities of the photos but my camera skills are poor!