Good luck! Can I suggest you watch the Horizon documentary that has been shown over the last 3 nights as it had some fascinating insights into the physiology and psychology of losing weight, I'm sure you'd find it helpful.
You can most definitely do it! You sound excited and determined about making these changes. I stopped smoking 2 years ago and have made some changes to diet and exercise as well and I feel a thousand times better for it. Life is about to get much better for you too. Well done!