We are very very stuck. We are completely sure of all three parts (song, artist, original artist) for three of the 20 songs, including one that was wall-to-wall on 6music a month ago. We have two parts of 7 more. Thanks, Google. There's one more song where despite not knowing song, original artist, or new artist, we're pretty sure we've got the answer right. That leaves nine that are a mystery. Including the instrumental, where I strongly suspect I own the original and may even own the cover but still have not the faintest idea.
He's looking for responses by tomorrow, and explicitly allows whatever form of research tools you want to use.