If you start working out, sleeping is sooooo important!
The secret, for being successful at losing weight and working out, is to do it little by little, one day at a time. As you said, you got really busy days, with 8 hours of classes, so I would wake up even just 20 minutes earlier, and add a routine during my week.
You don't have to do the same exercise every day, one day could be full anaerobic, another day cardio, and another day a leg day. Sorry I am talking too much haha!