When we operated out of Liverpool airport, ATC would always tell us of wake turbulence when at the take off point, and recommend the recommended interval before take off. Knowing that a) it wouldn't really affect us, and b) I would very quickly be clear of any turbulence, I would just reply "Roger. Ready for departure" and they would be happy to let us go. I've never felt any turbulence from fixed wing aircraft.
The latest CAP493, dealing with the revised separation criteria post Airbus 380, only mentions helicopters in regard to the problems caused by rotor downwash to other aircraft. It only refers ATC to helicopters landing after other helicopters that there might be a turbulence problem.
I've always been of the opinion(possibly wrongly) that the high speed of our "wings" leaves us unaffected.