You can make a start with these two: Martin Nail - English folk and traditional music on the Internet - Regional and EFDSS WebLinks. They both have links to various regional mags that are on the net. Be aware though that updating may not be that frequent - most of the paper mags appear every 2, 3 or 4 months and the corresponding sites are probably updated at the same time. You may need some lead time to get the listings in.

Mick