Oh I might get my gonads choped for saying this but don't take any of it too seriously just go out and enjoy the music and interpret it as you will , join in where you want to and listen where you will, don't be phased by thoughts that one might not be good enough, that really is not what it's about, it really is about folk getting together and playing and singing together, simple really. Last night a girl sang a heavy metal song, apparently. She had a good strong voice, her own voice, I suggested she went away and listened to the likes of Kate Rusby, Cara Dillon and Maddy Prior and then come and give us her views.
Point is, sing songs you like, songs you comforatable with, the thing about a lot of "folk songs" is that they have stood the test of time and there has to be a reason for it.