Hope this catches you in time:
There's a Games Workshop in the Bayshore shopping centre in the west end. Never been there, no interest. Anyway, it's incidental to...
Fandom II: this store is located near the corner of Laurier and Metcalfe, right downtown. (It's on the southeast side of the intersection, on Laurier, to be more specific.) Pretty much the only gaming store in town, aside from comic book shops. Really good store. It's believe it's open from 11 until 5:30 on Tuesday.