Okay, thanks Julian.
Whilst waiting for tools to arrive to continue my search for a leak, I thought that, as I've got the clutch in bits, I'd have a look at this (see photos attached). I think its called a cush drive unit and I'm guessing the rubbers inside act as shock absorbers when using the clutch? Anyway, to my inexperienced eye it looks as though it could do with new rubbers? I have some as shown which will hopefully fit. Is this in as bad a state as it looks to me, and what effect would it's condition have? Thanks again in advance.
Phil.