I think its supposed to be a different location in that episode based on a few clues. First, Sid mentions to Ivy that her relatives never come "down" (visit/patronize) to the cafe, which doesn't make sense if they are upstairs in the same building or close by. Second, Sid sneaks out and runs into Wally outside he and Nora's house but says he's on his way to Clegg's. As Clegg's was just up the stairs not far from the cafe, there is no reason for Sid to go all the way over to Nora/Wally/Compo's house if he was heading that way. More likely it means that at that point he and Ivy are living elsewhere.
Later on, such as in Getting Sam Home, we are shown them living upstairs from the cafe. We never see Ivy at home after that.