Today i priced up some 4 mm ply to do the room and its gonna cost over £135 to do what i want, So as money is tight as this is my first house and only moved in 7 months ago, i went back to the drawing board (ie all you advice)

So as a lot of people said that a good underlay will do the job fine, i took my self off to B & Q to see what they had, and before i left i measured the amount of difference between the highest and lowest part of the floor boardv which is about 4mm max,

B&Q do a 6mm thick underlay, which said it can fill defections of 4 mm just what i needed each pack covered 6 sq meters and i needed enough to cover 31 sq m, they had a whole 2 packs

Off to a different B&Q tomorrow me thinks....