As for me, i'm in High School, and i never had the possibility to speak with real english or american people, and i have two english teacher : one with an american accent and the other with an english accent, and i think my accent is more english, furthermore, i look Skins, and not Desperate Housewives =) may be it's the reason. Look, i'm bad in writing in english :s i'm better in talking.
Well, i hope i could come back here and made a big dissertation about my accent, one day, when i'll really speak English =D
(Look my wonderful school-transition : As for me, furthermore, Well... i'm ready for the big test (le bac ^^) !)