What should I take for breakfast?

I'm going to be starting a course which involves leaving the house by 6.30 to get the train. The train gets in an hour before my course begins (unfortunately the later one is too late) and I want to take a healthy packed breakfast so I don't have to get up at 5.30 to eat and so I'm not tempted by unhealthy and expensive coffee and croissants. I have no idea what to take though, I usually eat porridge or cereal but that isn't very convenient in this situation.