How to get the lead role in community theatre musical?

Okay here's the deal. Back in high school i never really got noticed at all in chorus. there were these 2 girls who always got solos so i just never really bothered trying for a solo. Well now im auditioning for Camelot and i have been working my butt off for auditions and practicing singing like crazy for months now. I really want a chance to show people that i can sing and i also love being on the stage. i had fun last year but didn't get a part. i was in the ensemble and i know i can sing. i have 3 choices for my songs: Loverly(My fair lady), The sound of music(aka sound of music), and Something Good( also from sound of music). my sister said she couldn't choose she said i sound really good. i want to wow the judges this time and i also need help perfecting a good british accent without overdoing it. I have a script i got online but i don't know if its the exact one they ll be using. i know almost all the songs and im trying not to get my hopes up because those girls are auditioning and they always get parts. My senior year of high school i didn't even get a part in our play! the girl who was a junior that year got the lead so im getting a little tired of competing for a role with her. any advice? clean please.