Just because you have had a bad experience, don't give up the idea of light aircraft flying. You've had some bad experiences with this school for sure, but to even think of using the voucher your friend gave you, you must be a little interested in flying? Or at least the experience (you won't have to take control if you don't want to!) My first flight in a llight aircraft was great as I had control flying some aerobatics and touch and goes - that was unusual fro a first flight I admit! But what i'm trying to say is as far as having control is concerned, you will only do what you want to do, and remember, the FIs hands are never far from the stick!!!!! I am 98% sure you won't be offered the take off or landing either!
If you start to learn to fly, its confidence more than nerve. I've had my ups and downs with training, and have thought of giving up many times (as these chaps on the forum know
) But i'm glad i've stuck with it. Find yourself a way to get airborne, even if its only once, and you'll see what we all mean!!