Thanks chaps.
Lon, the rooves are actually attached in three different ways as plans evolved, I really was winging it.
Firstly I attached 5 spars of dowel between the end walls/gables about 5mm from the lip evenly spaced to form horizontal supports but being an idle sod I reduced this to just 3 and then the smaller ones I used just one spanning the apex and used the tops of the front/back walls. All stuck with a no more nails/sticks like shit adhesive with a silicon gun.
Everything was done on a laser cutter. I drew each wall out and cut the frames, windows and bits in a fashion out of 5mm acrylic so I could then glue them back together recessed and proud to get a more 3d effect.
Hope that makes sense. If you want some windows I am sure I could find the time to edit the files and cut some for you.
Svennn