(T) oil warning light after head gasket change

Hi there

First of all, thanks to everyone who has contributed to this forum. It has been a god-send in the past. But I've got a problem I can't find any info on.

I've got a 51 plate Punto with 1.2 8v engine. The head gasket blew whilst on the motorway. Got towed home and stripped it down. The head was warped so had it skimmed. Noticed the coolant inlet fitting to the cylinder head (the bit with the temperature sender in it) was melted, so replaced it. Anyway, got it up and running but couldn't bleed the coolant system - steam just kept coming from the bleed point behind the temperature sender unit, until the temperature warning light came on and I gave up. I figured that I'd screwed up somewhere while fitting the new gasket, so stripped it down again. I found that one of the small circular coolant ducts in the head and the block was blocked with what I assume was the melted remains of the coolant fitting. I unblocked it as best I could, put it all back together and hoped for the best.

It started fine, heated up and I bled the coolant with no problems. It's got a bit of a rattle from one end of the camshaft, but otherwise it's okay. Except that the oil pressure warning light is on all the time and I'm a bit worried. I have a sinking feeling that I'll have to strip it down again, but can't work out what could be the problem. Could a blocked oil pipe/duct in the head cause a loss of oil pressure? The dip stick reads half full.

I'd appreciate anyone's thoughts.

Cheers