Well for starters, it has oil in it. Not sure when the last change was... a little while, but not crazy. It leaks so it gets replaced fairly often, although possibly needs to be drained. Might just go do that now regardless actually while I wait. Filter is pretty new although I have probably put a fair few more than average K's through it since then.

It sounds horrid. running rough definitely.

Mainly just wondering which order I should check things (of the things I CAN check.. I'm not afraid to get in there and go to town)... from most likely to least likely.

Cheers in advance guys ... this site has saved my ass more than once before!

OH. I *may* have noticed a quick bang/crunch sound when it came on. I can't tell if it was that or I just hit a piece of cardboard/something on the road.. Similar level of sound, didnt notice anything else. the light didnt come on at the exact point that the sound happened though (second or 2 after) and i couldnt see what was on the road cos was in dense traffic. So it may or may not have something to do with it.

OH. I *may* have noticed a quick bang/crunch sound when it came on. I can't tell if it was that or I just hit a piece of cardboard/something on the road.. Similar level of sound, didnt notice anything else. the light didnt come on at the exact point that the sound happened though (second or 2 after) and i couldnt see what was on the road cos was in dense traffic. So it may or may not have something to do with it.

I think you just answered your own question...

Check under the car to see what damage was done, if any, by whatever you ran over. You may just have dislodged the wire on the oil pressure sender. Or worse - but a good look will tell all.
If the engine is old and rattly anyway, before this happened, try the old fashioned 20W-50 oil and a new filter.

If you suspect you have no oil pressure, take the rocker cover off and start the car - briefly. The front chain oil squirter will oil the cam chain and it will throw oil all over the underside of bonnet. lol Bit of a clean up afterwards, but you will at least know you have oil pressure. lol Unless you have an oil pressure gauge of course, use that. Take out the oil sender and plumb the pressure gauge in that spot.

The oil pump runs off the bottom balance shaft, driven by a chain. If that breaks the chain ends up in the sump and you have no oil pressure. Shine a torch down the front of the engine with the rocker cover off, and have a look past the cam chain for a smaller chain down low. If that is missing you know what the problem is.

I'd unscrew the oil filter enough so it unseals and let the oil drain out then start the car and see if oil pumps out again.Only need to run for a few seconds.
Bit less messy than letting it spray allover the underside of the bonnet on the screen etc....... by taking off the cam cover.
Bit easier to clean up the front of the motor with some degreaser. Goodluck Vee