Went around with the poking stick and a magnet and found:
Worst part of the bodywork is under the headlamps behind the front bumper, pretty crusty but not holes and no filler.
Each corner of the front valance where it meets the wing is rusty and has been filled, badly. Not really a concern and replacement panels are available in GRP as steel parts are extinct.
Rear wheelarches, just the edge where it meets the wing is rusty, both sides. Also, not too worrying, more cosmetic than anything.
Wing tips, both have rust breaking though, these always rot out although there is no evidence of filler on mine. In no way urgent and very much repairable.
Structural metalwork seems to be in a better condition with there being very little corrosion to the sills or in the boot/footwells.
Mechanically the gearbox is a bit suspect with the synchro on 2nd being worn, but it is still usable and a bit of double declutch/rev matching never hurt anybody.
Clutch has plenty of life left in it.
Brakes are fine and operate evenly.
Needs a new rear wheel bearing.
Main problem is the engine that has worn away due to lack of oil. I have all the parts required to put it back together as my plan was to replace what was broken, clear out the sump and then flush out the old oil and see if it'll run. However, given the massive wear on the rocker gear (although I'll have to check the other arms) I was wondering whether to replace the whole assembly, but that's another ?100 for a brand new one, and the repo parts are far worse quality than the old ones.
Not sure I want to shell out that much on an engine that may have a terminally worn bottom end (although there wasn't any sound of bearings etc failing when it was running last). ?100 is enough to buy another engine, although that one might be as knackered as this'un...