Hey, I'm in the same position, I've been given advice from some chem eng students I know,
Basically what I've been told is to make a list of everything you've done, like Duke of Edinburgh or team sports you play, musical instruments you okay etc.., and explain how they have helped develop you as a person. But I also got told not not mention the same quality more than once as you are limited in the amount you are allowed to write(at least you are in scotland)