Can I Start Tae Kwon Do?

hey well im a 15 year old girl and recently i've become obsessed with tae kwon do! i have never done it before and im not flexible or fit but i really want to start... im am in love with the idea of being on the irish team for it,i would actually be the happiest child ever...well my question is if i do start is there any possiblity that i could get on the irish team eventually? how hard is it to get on the irish team? how long does it take to get a blackbelt? how long would it take to get on the irish team? pleeeaaseeee answer!