there is no rush to be honest at your age.
Actually there is the first step which does involve a trip to london and paying out 300 quid.
Your best to get a class one medical done to make sure you are not setting your whole life up for a goal which isn't possible.
Then work towards getting some form of qulification which allows you to save up for the commercial training. Realistically you are going to need about 50 thousand pounds worth of training to get to the point you can even apply for jobs.
The gliding has another bonus which is that you can tug for gliders which helps build hours cheaply so its good to get in with the a club with an aircraft.