So, further update: sorry for delayed all response been buying tools / parts to get it done here before the weekend.
Appreciated all the suggestions and encouragement.

GOOD NEWS! Taken the oil pump apart, cleaned up and fitted new gears (the old ones were not too worn but thought it best while out to fit new ones)
Packed the housing with vaseline, started up and now have oil pressure, about 2.5bar at tick over when cold.

BAD NEWS: I still have a tappet noise, turned the engine off after a couple of minutes, so the oil was not fully warmed up, just to be safe.

What are your thoughts on the tappet noise?
Remember originally the engine ran for 3-4 minutes at tick over before i hear tappet noise and turned it off, diagnosing the oil pump had lost prime.

Pics
https://ibb.co/7x8GL9G6
https://ibb.co/vCbgWdFW
https://ibb.co/nN1Lt2wq