Thanks all for the advice.
I should have pointed out that I have actually done the RAF's airsickness desensitisation course, and what you missed out crab was the lovely fast jet section of the course in the School of Aviation Medicine hawks! Now that's fun. The thing is that the course desensitises, but only if you can keep regular exposure to the flying motion and stimuli.
I used to be an observer in the Fleet Air Arm and so spent much time in the pitch black rear of the mighty Seaking, with some problems. However, that is over 21000 lb of airframe whereas a robinson 22 is only 1300 lb.
It is rare that I suffer too many problems in a C152 when I am flying, but it was a bit boucy the other day (smacked my head off the door!) and out came the bag. Very disheartening to have to end a flight prematurely. I now have enough money to seek a PPL(H), but from your comments it seems likely that an average robinson should be better than a 152. The next thing now will be a trial flight. Can't wait.
Thanks all
Obs cop