Paul,
MacColl always resisted calling any club he was associated with 'folk' or 'traditional' because he felt it would be to restrictive, and he never claimed his own compositions, which made up at least a quarter of an evenings performance, as 'folk - hence the name 'Singers Club'.
I have honestly never seen anything wrong with the term 'Song' or 'Song Club' - plain enough, no pretensions - it would certainly work for me.
Jim Carroll