Time for an update.
Split coolant pipe replaced and oil cooler changed and reassembled with Tunnie's help. Constant coolant flushes are starting to have an effect, as the coolant is now coming out fairly clear, with just odd oil droplets
Rear door central locking motor replaced with one from Ronnie McB, though door card not put back on yet as a previous owner must have had a go, and has knackered a self tapped hole.
Rear multiram repaired, and when activated with a Tech2 moves as expected.
Outstanding problems:
Rad fans don't appear to come on. Shorting out pins 1 and 2 on rad sensor brings on 1 fan, shorting 1 and 3 does bugger all.
Temp gauge has packed up (this was working intermittently when we put it back together, but hasn't worked for days)
Its holding back under heavy acceleration. I know its 'only' a 2.5, but it should go better than it is. The split hose would have sprayed water all over DIS.
Any ideas with these 3 issues?