I used the Screwfix version of foam on a garage coversion and a large front room recently and found it great stuff, Quick and clean and you can plaster on it almost straight away but only good if the walls are plumb as their is no play with it. With thermal boards buiding regs asked for 3 hammer in fixings per board incase of fire.The only thing to watch is that somtimes it does expand a little so keep an eye on it cos once its gone of you wont move it. Last thing on a Friday night i drilled through a cable putting in a hammer fixing in so just turned it all of (unocupied house) and had a right job cutting the piece of board out to repair the electric the foam had stuck fast.
Lucius
Lucius