Sorry to read this Ash.
I've experienced oil pump failure which led to big end failure on my96 Impreza WRX that I used to own, ...also had a snapped conrod go through the block on the same WRX some 12K miles later after I'd spent a lot having it rebuilt but that's another story.
When I had my problem with the WRX it wasn't far off standard guise at the time and therefore had no oil pressure gauge. It happened whilst I was driving along the M4 on the way back from Japfest one year. The car was running fine but then when I came to the toll booth to go over the bridge it just cut out at the booth, ...I restarted it and had to keep the revs up a little to keep it running but thought maybe it was a plug/spark issue at first.
I kept driving home hoping nothing would go wrong but then I started to hear a knocking coming from the engine. Before I had a chance to pull over the car just made a loud clatter/knocking type noise and completely cut out.
Coasted to the side of the road and called an RAC flatbed immediately as I knew it was something serious that there was no way I could fix by the side of the motorway.
Not a nice experience especially not as at the time I'd only had the car a month or so.