Wouldn't a failed HG mean a mayo like goo on the oil dipstick and excessive steam from the exhaust ? The car has neither of those and I checked the oil specifically for that when it happened today.

Weeks? It's a only a couple of hours of work, if that.
If it's possible to tow it, just tow it.
on a suspension note, my rear suspension is shocking! saying that though punto's aren't known for having great suspension and im guessing the lowered springs and low profile tires haven't helped much! regarding what happened to you with speedbumps, i personally think the amount of speedbumps and the height of them is getting ridiculous, near where i live there are so many of those speed 'hills' all over the place, car has just enough ground clearance to get over them without bottoming out.
local councils need to cut it the hell out with all the speedbumps like...!Fixing cooling/new rad. ( if the engine is not borked).
New clutch disc.
New front suspension ( simply worn, it's passed MOT but it's simply not practical at all), I rammed a hole in my exhaust because of it and my bumper scrapes over tall speed bumps if I go faster than walking pace.
Exhaust leak fixing ( basically has a MASSIVE dent and small hole in it, the place where the 6 pipes from the engine converge into 1 pipe, It smacked against a speedbump).
Neatening of rear left Arch.
New driver's seat and a good leather treatment overall.