Well I'm currently having a bit of a scary time

Almost two months ago now I parked the lude up as the oil light had flickered on twice and I was waiting for my mechanic neighbour who has access to a four post lift to swap the oil pressure switch for a new one hoping that's all it was.
The light had flickered on once when I pulled up in a parking space and then when straight back out again, which led me to checking the oil level only to discover it was below the minimum level only 6 months after I'd replaced the oil. And then once again two days after that (after I'd refilled the oil) on the second return journey from work. (It flickered on when I slowed up coming up to a mni roundabout and then when straight back off again). Since then I've parked her up and been waiting for my neighbour to swap pressure switches.
Anyway, after I put the pressure on him a bit over the weekend (As I need the lude back on the road so I can SORN the Aerodeck for a bit whilst I save up to get it's rust sorted). I started her up to make sure she would after being sat so long. I noticed the fuel was on empty, so I let her warm up and then went to get fuel. All this time the oil light remained off. I'm thinking this is a good thing! Pressure switch has obviously decided to sort itself out. But no sooner had I thought the thought it bloody flickers on and then off again. Just like before, it came on when I slowed up, but then as soon as I'm stopped it goes off again. Then gradually as I journeyed home, is started staying on as I was stopped at junctions and roundabouts, but with just the slightest bit on pressure on the accelerator pedal the light would go straight out!
Anyway, my neighbour finally got her to the garage last night and it turns out that the oil pressure on cold idle is a mere 25psi and then at hot idle it drops right down to nothing!
So there's two most likely scenarios...
1... The best scenario is it's just the oil pick up is blocked and needs cleaning out. The car was orginally running on 10w40 and when I did the change 6 months ago I switched to 5w40, which shouldn't really have caused any effect, but if not enough oil is getting through the pump might just be frothing the oil up.
2... The worst case scenario is the oil pump is knackered, in which case... jobby
I can't really afford to get it fixed if it's that, so I'm not entirely sure what would happen to her yet

If it is that the cheaper option would be to drop a known good engine in her. I toyed with dropping the Project's engine in her, but that's been sat for two years, practically fully stripped, so there's no guarantees with that one with out work on it. So I may just look at buying a cheapy car, but that would also mean I break the Lude (

) which has it's advantages with regards to the project (I can refurb and swap parts over), but I didn't really want to be doing that in my current setup of no garage and that'd be 4 cars SORN
So yeah...
