Nuts is a great answer -- add some walnuts or almonds to your bananas. And I'm sure the canteen must have oatmeal -- only a little you can do to mess up oatmeal, mainly adding sugar. Another thing you can do if you can get one is get a slow cooker and have it cook your breakfast while you're sleeping -- it'll be ready when you get up. You can cook some beans and rice -- most of the world eats beans and grain of some kind for all three meals -- or cook some real whole grain. There's gotta be time to eat -- it's a bit more important to your survival than a lot of other things you do, I bet.
Nuts
Also just remember u can eat what you want in moderation. And make small changes like if u eat in the canteen, that's fine, it will be healthy but avoid sauces, salt etc. Avoid high sugar drinks. If they give u massive portions u don't have to be at it all