You could pay a visit to The Kilkenny Tavern where there is a fine Irish Music session including Irish pipes - although in general anything goes (we have seen a Punjabi organ, stylophone and Scottish bagpipes there). Starts about 9-9.30 and finishes whenever (at least midnight and often beyond). It's free and there is some singing.

The pub is just around the corner from South Wimbledon tube. It is a traditional London Irish pub. The area is a bit run down but it is very safe and you can park easily in the side streets.

It is on every Tuesday and numbers vary from around 10 to over 30 - some fine musicians

Cheers

Sarah