When Sean first came into Corrie (as Todd's friend) he slept on the sofa in the main room off the kitchen. Jason and Todd shared a bedroom and Eileen had the other. As sons and other lodgers have come and gone there must have been a lot of shuffling of sleeping arrangements.
The 'front room' issue always baffles me. It only seems to be Chesney and Fiz's house that has knocked through, although they don't seem to have gained space by doing so. Since Les and Janice had that house the sitting room has had the front door at one end and the kitchen (with the back door) at the other. Oh, and maybe the Baileys' house, which they renovated when they moved in.
All the others cram everyone into one small room off the kitchen, and keep a whole room for no discernible purpose. I know that in the past people like Emily might have had a 'parlour room' that was kept clean and only used for visitors, but do people really do that now? It seems unlikely, particularly when the place is groaning with residents. They either knock through and have a larger room or use both rooms. The parlour room concept was mainly to save lighting a fire unnecessarily, but now that people have central heating it's much less likely that they would waste space like that.
I know. It's just pretend
.