UK, Ireland / Born in Poland. Obtaining British Passport? [27]

Hello there. My name is Michal Roman and I am inline speed skater. I am a member of the Birmingham Wheels Roller Skating Club based in Saltley and have been selected as a member of the national GB team to compete at European and World Championships. Last year I went to the Europeans in Italy, however there was a problem initially. I was born in Poland on October 31 1994, and have only moved to England on the 7th June 2005. To compete at European and World Championships, I need a British passport which I do not posses. Last year I was allowed to skate as an exception, but If I want to represent Great Britain again I have to get a British passport. I have searched around and found I would need to apply for citizienship? That would cost me 700 pounds, but then I would have to renew it in October as I turn 18 wouldn't I ? The other problem is financial as I haven't got 700 pounds to pay for this, as the sport is very expensive on its own, with me struggling to cover the costs of it. What do I need to do to receive a British passport, are there any funding options available for it, and do you know any sponsorship sources I could apply to for my sport? Thankyou very much in advance.