I'm not sure that you really need medicine. The most important thing is just familiarity and confidence - i expect most of us felt airsick at some point when we started training, I certainly did. Apart from that don't fly with an empty stomach (something light with lots of carbs is ideal, e.g. a bagel or some fruit - obviously that full English breakfast isn't). Ginger works well too, you can get it in capsules at any supermarket. If all that fails then it might be worth looking for some medicine, but I doubt it will be necessary.