Struggling to choose a career.

Tia • 18. Mixed race. Happy.
Hey all! So I'm 18 and I'm really struggling to choose what I want to be. I've studied hairdressing, didnt like it. Childcare, I liked it alot but I hated the nursery I worked in so I quit and never got the qualification.
So basically I like the idea of being a police detective but I live in the UK so its not as great as it would be in the US.
I'm interested in being a prison officer but I dont know how to get into that?
I also really want to work with young children (childcare or teaching assistant) or to become a youth mentor for teenagers and young children.. But I dont exactly know how to get into it/what qualifications I need so if you could help it would be great! 
Im currently working as a bartender and have been told in a year or so I could train to be a manager but the hours and everything would be way too hard on me plus I dont really want to stay in bars/clubs especially when I reach my 30s or have children! So if anyone has any advice it would be great