Business or no?

recently I've been interested in businesses, thinking of investments or even starting my own.

The thing is... I'm 15

I know I'm too young. All I want is to earn money to use as payment for my expedition to Nicaragua taking place next year.

Baking every other week is boring, as is car washing. So I thought about raising money in a unique way. Business.

I had an interview, I was told I had all the qualities they were looking for, for people to work with, but they turned me down because I'm only 15. It's understandable, because I need to focus on exams, GCSE and A-level. And then university.

They did however, say they'll keep my contact until I am 18 in case I want part-time partnership.

Anyway, are there any business that I could work with to generate with? Is there any way that I can earn money and not get bored of it?

UK answers only. (Preferably Yorkshire or general Northern)