Finding the right music

Since copyright will be an issue with deciding what song to use; I have to turn to non-copyright music. Websites such as www.overplay.com, www.unsigned.com, www.youtube.com have a host of unsigned talent that isn't copyrighted but would be polite to get permission off of. If I needed to contact an artist Twitter would be a good site to use to contact the artist since it has been used in the past to contact copyright artist and is mostly done to just casually contact their favourite artist. Since, I feel it is a pretty reasonable reason to use their songs I'm sure just explaining the fact that I'm a sixth form student currently doing my A levels and are in need of an excellent music video and that I would like to use their video to create my own promo music video.