Well, my question has been well and truly answered, guys. Thanks for that.
The answer is then to use a proper ladder and do the ridge cappings and those silly finials by hand, close up and personal. That makes perfect sense.
The other approach is to climb up onto the roof and walk on the spars. Personally, I wouldn't do that. Others may be more comfortable and confident on their abilities. I'm not - and that's OK.
I'm going to reserve a week toward the end of the month and try to get as many conservatory jobs as possible to make it worth while hiring a ladder so I can spread the cost - and hopefully have a really good paying week.
Cheers guys. Good thread.