Is the Thursday night session at the Newborough at Bontnewedd still going? When I was last there about 5 years ago it was very good with friendly musicians and singers.
Bontnewedd is about 1.5 miles South of Cearnafon on the Porthmadog Road. The pub is on the left at the Southern end of the village but the car park has a difficult entrance. I reckocn that is only about 15 miles from Llanfairfechan... Also there was a Friday night session at the Nelson(?) in Bangor, the people at Bontnewedd would know about that.