You can add up to 50 cubic square metres in volume, that will include the current dormer. The side window will need to be obscured glass and any opening over 1.7m above the floor level. Have a look on the planning portal, it explains a lot:- Planning portal

If I want to install Sliding Aluminium Doors (+ Toughened Glass Juliette Balcony) instead of the specified French Doors in the Dormer of a Loft Conversion (Hip to Gable) for a 2m x 2.1 m opening, would i need any additional structural support for the doors? At the moment we have timber frame with beams top /bottom and 2 100x100 posts either side.

Hi, I think your idea could work. Maybe it's the white render. If you were to use grey to match in with the windows the white up top and white under the middle top window wouldn't look out of place. I think it's because you've technically got three colours going on, that of the brick , the window grey and the render in white. Cutting down to two colours ie brick and grey, help it look more aesthetically pleasing. One thing:- I'd have a think about the layout of the furniture in the loft. With a whole wall of windows you will limit where the furniture can go. You may wish to consider getting rid of the middle section of windows. This will give you a larger area inside in which to site things like Chests of drawers etc. ( Just a thought )Or go for the one balcony window in the middle for more wall available in side.

It’s called a clerestory window. You’ll find loads of examples if you look for that. I think it’s a great idea. You could put trailing plants on the sill.