Work experience for psych degree

I hope to send my UCAS application off in a few months to study BSc Psychology degree next year. I have previously had a week of WEX in a nursery but what else will boost my application and show my interest for psych?

It's very hard to get relevant work experience for psychology when you are under 18 so admissions tutors don't expect to see it. You need to show your interest in the academic study of psychology, e.g. By having read books and articles, been to public lectures and talks etc.

Ok thank you! How many books/articles would you say is a decent amount?

You need to discuss them in your PS, not just name drop so you probably won't have room for more than 2 or 3.