I guess the consensus is, its not legal to advertise it as a roof garden unless planning is obtained however occasional use is okay as long as no one complains of overlooking or me being up there.
In terms of erecting a glass safety fence, Id have to take it down if I was selling with no planning for the roof garden. It may also draw attention to it and as a result complaints might be made.
The weight issue, I'm not too worried about as it was spec'd for taking people up there as even though we knew we wouldn't get planning for a roof garden we knew we would probably go up there on good evenings just to look out over the town.
I think that's most angles covered
You are taking up information incorrectly. Planning is not just about selling.
Why don't you just apply for planning? You should have the drawings from the extension so easy to do.