Well, thanks everybody!
Just an update - I did pick up my Explorer on the 21st and very quickly verified that the clicking was the AC compressor so thanks to kevin p and briwayjones!
Unfortunately I then had to have a recovery from London to Kent due to a corroded brake line leaking all my fluid onto the road, luckily I had not joined the motorway at that point! My garage did a speedy repair with a copper replacement for a good price.
I have a snagging list and tasks completed update, not really much use to anyone but I shall post separately should I come across anything useful, I'll put some pics soon too. I am not a mechanic at all but really want to do tasks on this myself, so got some tools, a good jack and some ramps to tackle simple stuff. So, TASKS/SNAGS:-
1. I did an oil and filter change. There is paperwork to show very regular oil and filter changes and other fluid checks so I thought I should continue this practice. I went for Mobil1 5W30 fully synthetic and a K&N filter, both of which I got for a great price and free delivery off Amazon Prime. I was happy to see no evidence of contaminants when I changed it. It runs great now and is still super quiet.
2. There was a clunking from below the vehicle that I mentioned in the previous post. After examination the NS Sway Bar Link has lost its top nut and half the bush so this was clonking - not the exhaust at all of course. I have removed it and ordered another pair. Pretty happy with myself for this find!
3. The ARC suspension light comes on after approx 20 minutes driving, it resets on ignition off/on. No apparent issues with the ride, and the rear of the vehicle does not look particularly low (maybe a touch). I have jacked up the rear and floated the wheels with ARC off, dropped it and switched ARC on as I have read on this forum. Sadly, after a quick test drive the light still comes on. The rear shocks appear to be quite corroded, but not investigated any further than this.
4. Got the 5000 RDS radio to work, with a code and some button combinations. No radio signal (antenna still goes up when lights turn on!) but at least the CD changer works. I will check out the rear connections then the aerial and try figure it out.
5. I have ordered a set of General Grabber AT2's in 265/70R16. I always wanted some for my old Exp before I had a crash. I'll be holding on to the tyres that come off as they are quite good - Kumho 255/65R16 M+S rated road tyres.
6. Still need to swap rear wiper motor.
7. Got a quote for tinting windows from B-Pillar back for £140 all in. I know they are good as I got the contact through trusted work recommendation. London based workshop.
8. Really want to do the timing chain tensioners too even though it is running quiet at the moment. I'm on 118k miles and I have no evidence they have ever been done.
Thanks for the welcomes to the forum too,
Toby