Vicki-
Sounds like the gym is going to work great for you. I prefer working out at the gym, because you get in that zone once you are there--I get so distracted working out at home. Plus I love using the machines as I find that seeing how many calories you are burining, really gives you motivation to make good food choices throughout the day. Once you see how much effort goes into burning 300 calories, I find it becomes a lot easier to resist bad snacks that are just empty calories.
Good luck!