Right then, this is more for any future readers. This scenario caused me massive distress over the weekend with the thought of the financial consequences. I'm talking sleepless nights, shakes, etc. I'm not a rich lad and I've a family to think of first.
Got to the garage today after not touching it since Saturday when all the alarms and Knockin rattling lumpy idol etc started. Started it up, sounded horrible, however within 6-8 seconds it returned to sounding normal, although if revs we're raided to 2k, it returned to sounding like a tractor missing a cylinder, indicating that the oil pump was in fact still working and it was only struggling when it really needed to suck. So we put a Forte flush and left it idling for an hour with a close eye on it, drained oil, took sump off. And there it was, pickup pipe sludged to the hilt. Took it off, should've replaced but couldn't get one local for love nor money, so I left it in a bath of brake cleaner while I cleaned the sump out. 20 mins in the cleaner and an air line, it's like new. Refit, new oil, filter, plug an washer, cautiously fired her up. Amazingly no lasting damage!!! Drove ten miles home, eventually grew the balls to give it a boot full, absolutely fine, smooth as feck.
Just thought I'd update for anyone else who's head has fallen off with the posibilities of what might be. For those interested too, oil pump from ECP is £74, pickup pipe from TPS is £11.50. Bare 225 engines start at £499 on eBay. I priced all these options just in case lol. Consider myself extremely lucky.