Hi Simon,
Don't envy your situation at all, but can sympathise - my daily driver (SAAB 9-5) just died - electronic fault apparently
- sounds like it could be expensive!
As far as yours goes, you would only get water in the
oil or vise versa if the gasket blew between these two points - if it blows between the combustion chamber and one of these you will not have the same effect but blow
oil or water out of the exhaust.
Sounds to me like you may have blown the gasket between the combustion chamber and out to atmosphere (edge of cylinder head).
When that rocker came off and the exhaust valve (it was exhaust wasn't it??) couldn't open - the compressed gasses had to go somewhere and they shot out a weak spot in the head gasket.
This could sound (although I'm not sure) like a slightly blown manifold gasket which would be like a "ticking" sound - which could be the sound you are hearing
It's a possibility - and not an expensive fix, but would be difficult to notice, I would think, by looking at the gasket (unless it had been run for a few months like this - which yours hasn't).
As to whether the head would come off easier or not - I really don't know, and doubt it as it would need to affect the whole gasket area - fairly unlikely I would suggest - unless someone else knows better????
Good luck
GUMBALL UK (Sean)