I'm not good at all hun. I struggled with my weight for over a year after having Niamh and used to weigh around 230lbs. I used to cover myself up with big clothes, eat what I wanted and never looked in mirrors.
I used to be the most unmotivated person, and eating junk helped me feel that way. Sluggish and unable to do anything about it.
If I can drop the weight though, anyone can.
Good luck with the exercise after class

If you're going to walk on the treadmill, put it on a slight incline. You won't really notice it, but it will be working your muscles more.
We do have the Biggest Loser over here, I love it

Good luck with your 'last chance workout'
As for eating, you should eat complex carbs about 2 hours before a workout, and ideally have a protein shake straight afterwards (no more than 30mins afterwards)
Carbs will provide you with energy before your workout. Carbs break down into 3 different types of sugars, and this is what provides your body with fuel for exercise. Carbs also help your body not use protein as a form of energy. They must be complex carbs though. Brown bread, skimmed milk, leafy greens, dried fruit, fruit, museli, whole grains, etc.
Protein straight after a workout is fantastic. It will help your muscles recover quicker, but will also help you lose weight! You need to have a proper workout though, ie sweating and working hard

Protein will help rebuild muscle tissue faster as it has extra amino acids in it. You will also get an energy boost. Protein gives your whole metabolic system a big kick, which means you will burn fat more effectively while retaining muscle protein. It doesn't have to be a protein shake, these just give you a much higher concentrated amount of protein than found in food. Just eat something very high in protein as soon as possible after a workout.