I got the manifold off, it took some doing!
I’ll bathe it in brake fluid to clean if tomorrow, while it’s bathing, I’ll make a start on cleaning up the cylinder head, at least mating face, ideally I’d like to clean the inlet ports, but I’m a little dubious about bits falling into the engine, some of it can be quite hard.
The suspected hole in the manifold turned out to be a split front EGR pipe, rite where it enters the inlet manifold, so that will need replacing, both bolts on the other end of the front pipe sheared off, so it NEEDS to come out now, just not sure if it will go back in or not yet.