Thanks for all the replies! Funny how a thread takes on a life of its own!
I've heard some different opinions on osmosis, I'm inclined to be a bit more relaxed about it, whilst still keeping an eye on it.
One other thing I wanted to ask is how damp should you expect a boat that has been left locked up and unused over the winter to be? I have looked at a couple of boats that have drops of water hanging from the headlinings. Both these boats didn't appear to have great ventilation, and this was after a spell of very wet stormy weather, so I thought it wasn't anything much to worry about. Was I right in thinking that or would that be another potential warning sign?
Once again, thanks for all your help!
Cheers, Matt.