Please help !!??

well i havn't had yet im 14 and i can get laid by thi girl but i am afraid my condom will split..what is the safiest condom...i live in england by the way so english makes will do...and what are ways of avoiding spliting condoms....like if they are too small or too bigg do they split and once i put on a condom it felt tight but it didn't go down the whole way is that safe ???? please help thanks