OK, an update on the airbag issue. Don't want to jinx it completely, but....

I think I've cracked it

Bought an air bag module from a vehicle without seat air bags. it needed slight modification to it's plug socket, just cutting away two bars on the side of the drivers side socket, and plugged it in.

Tested it and the airbag light came on, but no flashing, and different codes which suggested there was a bad earth. That was because I'd just plugged it in and not bolted it in. Battery off (again) and bolted it in and trad again, and, NO AIR BAG LIGHT

checked the codes and it was still showing the bad earth codes, so cleared them, and Robert's your mother's brother, no more codes, and the light is still off !

Will give it a road test and confirm in a day or so, but I think that is finally it

Next job will be looking at the suspension, it's been lowered, and I want it back to normal but stiffer and more heavy duty, a la 70s escort rally set up. It might seem crazy, but I live half a mile down a rough farm track, and am an on-call firefighter, so every now and then I have to drive down the track at a fair lick......