Footstompin is a Scottish music forum, you would be better trying a specifically Irish one (thesession.org is mostly that). One place Irish sessions happen is the Clutha Vaults in Stockwell Street, and somebody there is bound to know what else there is. There is a long-standing locally rooted tradition of Irish music in Glasgow, but you may have a hard time finding it behind the crowd of wannabes who learned everything they know off Chieftains recordings.

You get both Scottish and Irish music at the Saturday afternoon session at Babbity Bowster's (near the Tron). For my taste there's too much not-very-interesting Irish music and you can get a situation where the musicians might as well have table flags, with almost-non-overlapping subgroups playing Irish and Scottish sets alternately. And the place is helluva noisy.

Look at my website for a collection of utterly basic Scottish session repertoire, it would be a good idea to know at least that much.