I play regularly at a local session i.e. a group of musicians and singers of mixed ability all playing/singing "folk" music, whatever that is (but that's another topic). There are basically no rules and no one is in charge but it works. Newcomers are welcome and, irrespective of ability, are encouraged and over a period it's great to see how people develop confidence and their singing and playing improves with this added confidence. Professional/semi professional musicians from Ireland visit when in town and have the attitude "it's a session -anything goes". This to me is what a session should be.
The session at Howth (see fidgiit 7th July)is really good and welcoming, not like many of the other Dublin sessions where is paid artists who don't want , and certainly don't encourage, participation.
Unfortunately I believe the Lighthouse has closed.