Right, update!
Got the rocker cover off finally and rear pedestal stud has 'most likely' pulled/stripped out of the head.
Now stuck cos can't get rocker shaft out cos not got 10mm spanner/socket!
Have called AA but typical bull**** gotta send a patrol and then if and when we might get a flatbed.
Personally I'm dying to get this rocker shaft out to inspect the damaged hole and recover the valve stem caps but my mate just kinda wants to go home
The other thing is the patrol might say (this has happened before) that seeing as I've worked on the car they won't touch it!
Might be in need of help yet chaps, thank you for your attention thus far!