Totally agree with all the comments so far re early students. But Jolly Jumper says:
I'm am already a PPL
So I'm guessing what we've got isn't a case of someone gripping the controls; more likely Jolly Jumper either doesn't have the aircraft trimmed properly, or else is making too frequent corrections in choppy conditions.
I would suggest a half an hour of so of straight and level flight without touching the controls at all. Just use very small rudder inputs to keep the wings level (secondary effect of rudder). If you find you are climbing or descending consistantly, then you need to review either your mental picture of the straight and level attitude, or your trim techniques (one of the most common problems being trimming at the top of the climb before reaching cruising speed, resulting in the aircraft starting to climb as it picks up speed, for example).
Hope that helps,
FFF
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