I have made a mini library under the category 'Conservatory' and I have used the principle of making the conservatory using walls. I specify the height and thickness of the conservatory wall and then snap windows, doors and glass to it from my category.

I am not the best at it but my conservatory looks ok. Using the wall method rather than free flowing everything is a lot easier and you can make a real room.

I have not got to the roof yet.