Milsey, I know what it's like to be in a frustrating job, believe me. So I can understand you wanting to get started on your career of choice.
But you really need to look before you leap. Make out a business plan that shows how you are going to pay for the training you need, and be realistic about your employment prospects. The plan should show (amongst other things) the rate at which you have money coming in and when you need to be spending money on training.
Making the plan and getting it validated is a vital first step and will feel like progress.
Other 'first' things to do are the GAPAN aptitude tests, and getting a Class 1 medical (at Gatwick).