For a typical 100mm wall; you will need 2 formers 70mm wide cut to the radius of your curve.18mm mdf or ply will suffice. These will form the head and sole plate of your wall, you can then screw 70mm studs at 600mm or 400mm centres, depending on your radius, to the head and sole plate. The framework once positioned can then be boarded both sides with 12.5 mm plasterboard. 9mm plasterboard is available if the radius is tight. This framework can be insulated in the normal way. Hope this helps