Hi,
A good resource for sessions in and around Toronto is Wil M's Toronto Celtic Music resources page.From memory there is one Sunday late afternoons at Dora McGeogh's on the Danforth. The Comhaltas hold a session every 2nd and 4th Wednesday at the TRANZAC (they break for summer). Also at the TRANZAC, though not trad, is a Gypsy Swing workshop on Monday's (with a jam or suchlike on Wednesday's)
There is other stuff as Black Walnut stated, and maybe she or others can help on that.
Rana