Flat or pitched roof to extension

[Ash1]

Hi all,

We are doing a 6m deep rear extension and could really do with your thoughts _/\_

Our adjacent (party wall) neighbour currently has a 3m extension with pitched roof. 

We are looking to match the neighbours pitched roof (with pitched internal ceiling below) and then transition to flat roof (with flat ceiling below) for the remaining 3m. The pitched part of the roof is to have a large skylight/velux to let light back into the original house. Now I searched everywhere to see what this may look like and all i could find are either pitched ceilings or flat then leading to pitched, not pitched then flat.

Would be very interested in hearing peoples thoughts and ideas and whether there’s a reason for not being able to find something similar on the internet.

Many thanks