Thanks Zanshin and PCP.
I'm starting to get my mind around the problem now.
The other thing I have found out is that I also need to get an "NIE" which is a Spanish Tax ID number. This seems to be needed by the yacht buyer, and would appear to take many weeks to get. I have to go to Spain, present the application and supporting documents at a (suitable) Police Station.
Then, some weeks later (between 1 and 6 I believe) my NIE will be ready for me to collect. BUT they dont tell me when its ready, I just need to go back to the Police Station from time to time and ask if its ready! Hilarious!
There are apparently other ways to do it through the Spanish consulate in the UK, but they all seem to take many weeks. Seems like my thoughts of flying in to Spain on Monday, and leaving on Friday as the new owner of the boat are somewhat pie in the sky.
Zanshin, I'd love to do this stuff myself, just for the experience, but I have almost no Spanish language, and I am not resident there so I will probably need to retain someone to work on my behalf.
I think I will go and start the process on Monday by viewing the boat and getting survey done, and maybe by spring time I will own the boat
I'll keep the thread updated for ayone who is interested in the saga!