For something this small a square meter rate would not be that good. The proportion of waste boards and the amount of timber for wall, floor & ceiling plates would throw the calcs out. Also depends on what length you can by your studs in at as to how much waste to allow

Easier to draw it out to scale & workout what you need, timber plates all round perimeter and doorway, studs at 400cts and one row of noggins should do.

Assuming your ceiling is not over 8ft then work out how many boards across the room & double it, ignoring the door opening.

On a clear run 3.6m of studwork per m2 works out OK with the right length studs to give no waste.

Jason