Re-design of rear dormers to loft conversion

I am carrying out a first floor and loft extension and need the loft re-designed to maximise the floor space by extending the rear dormers as much as possible. The roof is in different sections so this isn't a typical single rear dormer extension. I am only looking for the re-design of the loft room and nothing else so will need sections and revised elevations to enable the builders to work from the drawings.

Ready to appoint ASAP and only UK based designers please.