AeroMad, Unfortunately, underslung load lifting with helicopters is a specialised thing, it's not allowed by law for an unqualified pilot to just "have a go". Rope is not used; the design and use of the lifting equipment (e.g. steel wire or nylon strops) is controlled by law.
We can't hang any old bit of rope on an aircraft for jobs such as this, by the way. If it breaks under tension, the part attached to the aircraft may well fly up into the rotors and you will have two recovery jobs, not one, at best.
It's going to cost you dearly if the military won't do it and I am certain they will not even attempt it. For example, a TV mast was recently repaired near Oxford. I understand a helicopter was brought it from Sweden to do the load lifting.
Hope the roof restoration of the house is going well.
