Aston villa football acadamy?

How can i join a football acadamy in birmingham.yesterday i went to aston villa and they said u need write us a letter?? im 15 now and gonna be 16 in 3months i want to start before i turn 16. anyone who goes to a football club in england(premier league clubs- tell me how u got in der . is it to late to be a footballer at this age(15)??and i have also a coach from aston villa hu comes to my school ,he said u can go to the acadamy if u fill a form in and he keeps saying i will put u in the acadamy but his not.??plz answer thanx.