loft conversion - has anyone extended above height of roof for a dormer?

Hi there - we have a loft room with a low ceiling height (I can stand in the middle right below the top of the roof but everywhere else i have to crouch down). Its already been converted into a room as part of the rest of the loft conversion but at the moment not able to be used as much aside from perhaps a playroom for the kids due to head height. it is a big space in terms of floor though so would easily be a double bedroom if there was a dormer to the back.

We could lower the height of the below bedroom but i want to avoid that if possible (because the bedroom so i was thinking about perhaps giving a dormer conversion a sloping roof upwards from the apex of the roof (or perhaps flat from the apex, eventually going higher (to avoid being able to see it from the front (for the planners). I know this means i would need planning as doesnt qualify under permitted development but i was wondering if anyone had ever done this or (for any local architects) if the planning people would just laugh at me.

If its a function of impact to neighbours, its worth noting that the dormer would be adjacent to a neighbour whose house is higher than us (they have a cellar and we dont so effectively almost a storey higher) so we would be nowhere near their roof height/overhang. I guess there would be some impact on them sunlight given our houses face east south east but there also wouldnt be any on the neighbours the other direction who have a roof height the same as us.

Sorry its turned into a bit of a ramble. Nothing urgent, but with a growing family who love the area, I am looking at options! any experience or views from professionals very much appreciated.

Lockers

If you can stand at the highest point would a dormer not extend from that point?

We are in the middle of a loft conversion the height in the centre of the room is the same as the height in the dormer... it is still quite low at 1.85m but luckily that is higher than we are tall.

"If its a function of impact to neighbours, its worth noting that the dormer would be adjacent to a neighbour whose house is higher than us (they have a cellar and we dont so effectively almost a storey higher"

Don't think it works like that, height of house is measured from street level, not from the lowest point within the property.

Depends how tall lockers is.

Ours is 185cm which meets building regs (clearance on the stairs has to be 2m though). The min for the actual loft is either 180 or 185 I can't remember but I know we meet it.