Trying to Work on an Exit Strategy....

So for context, I am in my last class for my pastry chef degree...I tried finding a job within my company for my externship, but one problem... My store manager. He doesn't want me to leave because I am one of the only stable workers at the tiny gas station I work at (I mean it. I am the only stable worker at that gas station, and everyone alternates from the other stores)... I mentioned that I was trying for two food management positions. The problem is that my boss isn't approving me leaving to go to another store even though it could help me graduate. He has been laying on a guilt trip every damn time I find a position at another store which I need for my externship.

Another thing... Despite the fact he is having me train people and tells me I do a really great job he won't promote me.

I did get an interview with a hospital cafeteria. If I get the job, I am peacing out. I am also doing volunteer work for a food bank in town making hot meals which I want to do beyond my externship because I love helping people and want to make a difference where I live.