Know what you mean about it being horrible stuff. Shifting it about while setting packers out at the eaves was an experience I dont want to repeat again. Its fine as long as its not disturbed. Remember you have to seal your living space from the loft space in order to prevent damp problems. Warm air getting into your loft space will condensate and bring dampness. The loft needs lots of venting (see the vents I attached on one of the pictures) I also have soffit vents at 450mm spacing (Cheap as chips) The foil insulation board has to be taped to produce a vapour barrier into your loft space. The celotex foil tape is garbage as far as I can see. In a week its slowly debonding so I have taped it all then will use a polythene vapour barrier on top to go over board safe. The 22mm chipboard flooring has glass wool underneath but is also sealed with wood glue before being screwed down. I also have sealed loft access doors to install.