So thanks to the lockdown I can survive without my car and my mechanic (who works on his own, in his own unit) has spare time.
I'm thinking that now (with 125k miles on the clock) would be a good time to have the various fluids changed that are not normally done as part of a service.

So far I'm thinking:

Transmission (I believe that in the absence of the special machine, the best way of doing this is to replace the sump pan, filter and gasket, drain and refill twice, does that sound right?)

Front and Rear Diffs

Transfer Case

Also going to have anti-roll bar bushes replaced and any other worn suspension components changed as well I think.

Anything I've missed / recommended to be done at the same time?

In the absence of a flush machine, emptying the oil twice is the usual way. It doesn't do a full change, sadly, as most fluid is "stuck" in the torque converter. Might be worth leaving that until you can get to a flush-equipped garage. Changing the pan/filter doesn't seem to be that useful.

The transfer box and diff oils should be changed as part of the service schedule, although it's not very often it should have been done at least once by 125k miles. No harm in doing it, that's for sure. Good chance to check all the seals on the diffs and transfer box.

Suspension bushes is a good plan.

Perhaps the flexible brake lines? How about brake fluid change? 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

and a Power Steering fluid flush..? Siphon off some, add new, siphon off some, add new, repeat. Alternatively, drop the lot, fill, bleed etc. Visitor from fullfatrr.com
* GONE. 2012 RR Sport HSE SDV6 Orkney Grey. Now being piloted by RRSTDV8
* Current: 2011 4.4 TDV8 Full Fat. Amazing piece of kit.
* Current. 1974 Lightweight 2.25L petrol. Old skool
* GONE. Freelander GS TD4 Manual MY2013. Orkney Grey with privacy, cold and clearview packs, armrests (a must!) and a spoiler.
* GONE. Range Rover Classic '93 200Tdi Factory fit
* 1949 80" in family since 1975

Gearbox fluid - don't just drop from the box and refill, you won't get enough out. Replace all of the fluid. It isn't a complex or difficult job to do and you do not need a flushing machine. It's easy enough to do this yourself with a pressure sprayer, some hose pipe and an hour of your time on your driveway.

See my step by step instructions I posted in this thread... https://www.rrsport.co.uk/forum/topic54619.html

Also consider:
Engine oil
Coolant
Transfer Case fluid
Front and Rear Diff oils
Power Steering fluid
Dynamic Response/ACE fluid and filter
Brake fluid
Air filter
Cabin filter

But all of the above are on your service schedule. For me, I replaced the lot and started from fresh for piece of mind.

PS. the gearbox cooler is just underneath the front bumper. Kev

MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

I’ve just had a major service on mine and it only has 77k but is 14 years old. Coolant change, brake fluid change, cambelt + oil pump, front diff fluid change, TB & rear diff done last year and finally some rectification work.

Mines a keeper and it feels better for it. 2006 2.7 TDV6 HSE in Cairns Blue.

Thanks all.
Service history reveals one or two of those done recently so my list looks like this

Normal service
plugs
F+R Diff fluid
Dynamic Response
Brake flexi check and replace if needed
PAS Fluid
Gearbox oil
new coolant bottle
Anti-roll bar bushes
Steering rack replacement
Whatever other suspension bits are found

How come you're replacing the steering rack, Derek?

If you haven't already got a rack, a few of the guys over on the Disco forum have reported good things about recon racks from Lion Automotive https://www.lionautomotive.co.uk/ Kev

MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

Replacing the rack as there's a bit too much play in it for my liking and my mechanic picked up on it being very worn at the last inspection and advised that replacement would likely be needed.

Whilst I probably could carry on with the current one for a while longer, replacing it isn't going to be a short job I imagine so I might as well have everything done whilst he's in there!