Now lets get down to business

The business of determining what has to happen next, of course! I have determined that i can get the cash I need if I find the right part time job. (any opinions on Ingles?) The next thing I have to do is convince my mom. Every time I bring it up to really talk with her about it I get a vague "we'll see..." or just flat out NO. She seems to be wavering but I'm not sure. I have explained to her that I will go after my senior year and that year's summer and the following Fall and Winter. I will be 18 when I go, I DO have much common sense, and I'm a hell of a lot more cautious than most teenagers. So now my only question is how to get her to let me go? Both to England and her vision of the little girl she thinks I am...any advice?