In the US we have a program in school, well at leaset in my school that I went to, where we shadow somone at work. And we get credit for it.
Find out at school if there is anything like that. Than ask your teachers ask people in the school office if anyone knows a lock smith that you can go to work with.
Ask your career counselor (if your school has one) ask if there is a lock smith you can shadow. Even if your school does not have a work program, you still might be able to get school credit for it.
DON'T SAY YOU WANT TO LEARN LOCK PICKING.. Not a good idea, they will think your up to no good.