Thought I'd give an update, since the ownership has got a lot more positive in recent months.
McLaren Ascot (sales) did agree to swallow the cost of the climate unit as goodwill. While we were discussing the fact that they should be doing this, I stated that the most likely reason water had damaged the climate unit was a leaking seal - and that they MUST check that's not the cause. I was told that they had checked, but would check again.
Got the car back with working climate, and went to a PH meet. Not long after getting there it rained quite hard - once it stopped, I went back to the car to put my sunglasses away. What did I find on the climate controls in the door? Water drops........
Straight back to McLaren where they apologised profusely, and replaced a seal. Initially, it still seemed to let a little water in - but this stopped after a few days, and the car then seemed water tight.
Since mid-December, the car has actually been pretty well behaved. The windows can be a little random occasionally (they'll go all the way up, then drop to halfway) - but it's rare and not something I expect them to fix when it hardly ever happens. Apart from that - it's pretty much fault free - even stuff they haven't fixed (e.g. drivers mirror failing to fold out properly occasionally) doesn't seem to happen anymore. Owning the car has been a lot more fun when it "works".
A few weeks ago, I got the alignment done - and although it still takes a LOT more initial turning of the wheel than the 360 does on the same bend, it has sharpened up the handling and it feels like there is a lot more front end grip.
On the way back from the alignment I stopped at Ascot, because I was not happy with the paint. In bright sunlight, it's perfect - but in less than bright sunlight the bonnet looks darker than the wings. There are a couple of other panels where there is a very slight difference in shade - not as noticeable, but once you've noticed it..... Ascot say that the car has had no paintwork under warranty, and that they did no paint as pre-sales prep.
However - within a couple of days, McLaren Client services said that they will cover the cost of the car being painted. I don't believe they are going to do the entire car - but I have been assured it will come back as a single colour and will be perfect. It's actually very common for McLarens to need panels painted - manufacturing problems mean they suffer from bubbling - so the paint shops are very familiar with matching the colours! I think that at the very least, my entire front end + LHS of the car + engine lid is being done (and probably the front roof panel too). I think this is entirely down to fading which is a bit worrying - I've been told that the formulation of the volcano colour paints changed and the earlier cars (which I suspect my 2014 one counts as) are more prone to fading.
Since the car will be perfect once it comes back - and the stone chips it's got in the last 6 months will have gone - I'm 95% sure I'm going to get PPF over the entire car once it's painted. The 5% doubt is because it's damn expensive!
Car will be off the road for most of March while it's painted - which is particularly bad timing, because the Ferrari needs servicing in March too - and will probably then go up for sale.