We have a training area that is very much the same (not in the UK). I have never felt the slightest upset from a departing fixed wing.
We adopt the principle that if we start the climb out from a point before the fixed wing rotates, with our climb angle being steeper and the fixed wing wake always descending then we shall never meet. Similarly with the approach ours being steeper, we shall always be above the fixed wing wake.
However, we have had complaints that regional turboprops feel the effects of flying through our (Enstrom & B206) wake!