.....traced my oil leak!

.....yes, the cover plate has only small bolts so I guess are just pinched up enough to sequeeze the gasket.

Well.....that was a bit more involved than I thought it was going to be!
More bolts to undo than I expected and some of them quite difficult to access. The old gasket was definately made from thin rubber. It was suggested that it might be an old paper one that's just been inpregnated with oil over the years but it was deffo rubber.
I've replaced it with a paper one.....it does make you jump a little when you break the seal and you hear the valve tappits drop down!....LOL
Additional bits I needed to remove were the black plate behind the cam pulley with the timing mark on as there was a bolt between it and the pulley and the two bolts from the side engine mounting that I guess stabilises any enginemovement as it's bolted to the cam housing.
Getting the cam belt back on was a faff again. At least the crank and cam pulley timing marks lined up afterwards and it runs. I think I've moved the pulley that drives the distributor rotor arm again. I can set that up again later but it runs okay.
The cam cover gasket was also a bit worse for wear so I've ordered another but thats a quick fix now.
Thanks to everyone for all the advice.....it really helped......another job done and more X1/9 skills learnt!