Thanks for the votes of confidence, its nice to know other people are following, makes it all the more likely I'll actually get this project finished.
We do feel lucky to live in such a nice area, but its taken a number of years to get the house refurbished.
M40, I'm not planning to put any mains power in the observatory. Instead I'm going to use 12v battery power and attempt to modify a car alternator for wind power to charge it. (Stephenstargazer got it spot on)
My brother lived in Florida for a number of years, and I know it has other benefits!
Next job is to dig 6 smaller holes for the main support legs and get the concrete in, but that will be a few days away, I'm still aching!