Hey folks - thanks for the replies (and mega thanks to the people who've already mailed us).
Re: Creative Commons - a lot of stuff is licensed 'no derivatives' 'non-commercial'. Technically including in the programme is a derivative work, and as the programme is going out on a commercial radio station in Ireland it could potentially violate that aspect of the CC licence too, so we need to either have explicit permission from the artist or use public domain or CC0 licensed stuff.
We'd really appreciate any links to resources with chip music under those licences.