Some more info:
The below sketches are inside dimensions, I have raised the ceiling hight 300mm (1 foot) above the back drop wall, from the wall to 1m. This will allow me to install back drop rollers up a little higher, above the normal 8 foot ceiling hight. I may also mount lights up there to colour the back drop wall, for top (hair) lighting etc.
I also built a recess in the left wall, 1100mm wide x 8mm deep, this will allow me options like a strip soft box side light, to back light, etc pending where the subject stands. Doing this allows a little less confined stage area.
I will be installing ceiling spigot mounts on the ceiling near the back trop end, to allow easy instal and placement of strobes in either corner or middle.
I will be installing a ceiling rack with 3 pantographs for lighting facing the subject, this will allow me to keep the floor clear and obstacle free and provide various lighting options
I am looking into covering the concrete floor with a while gloss epoxy finnish, this will give an extremely hard wearing, clean surface. I will most likely also build a collection of lino and carpet that can be rolled out for different scene.
I like the idea of a curved floor/back wall joint, Im not sure how to make this, any suggestions would be appreciated.
I am still unsure of what colour to paint the walls, ceiling, back drop wall.
The space is small, I think white for the back drop wall would suit best, and use lights and/or rolls to provide various colours.
I like the idea of white for the other walls and ceiling also, but still unsure, may be a light grey to add some contrast to the room. A little less clinical.
I'm not apposed to black, if its going to make the difference, give me a lot more lighting control. Unfortunately I haven't experience to know how much difference it can make.
The windows will allow natural lighting also, but they will be fitted with blinds to block out light when needed.
Anyway, I have sheeted it all, I'm starting to set the drywall, then time to decide on paint..
Floor plan

Glass Sliding entry door
Outside wall
Some 3D views