Im sure you wouldn't put your husband in the garage! If he does work from home a lot though he may well not want to be in a open plan space? Just a thought! A couple of other options. Option 1. Lounge in extension with L shaped sofa on back wall and tv above radiator (assuming this room is wide enough as forgot to ask). Study area in one of those cabinets that close in the recess. Play area in middle. Dining room in current lounge with extra seating for relaxing and /or you could also consider the desk in here. It does mean you take advantage of the garden but I assume the kitchen is near the extension end so may not work for dining. Option 2 is basically what you said. Dining area in extension with desk in study area and a chair by the window corner. Play area in middle. Lounge in existing place. I'm not convinced an l shaped sofa would fit, only place would be where the existing cabinet is but then where does the tv go. Or option 3 is to combine play room and dining as Lucinda said but with a permanent table. In whichever the biggest room is. There was a recent post on this and some images posted so could try and find them if this is an option. It's a great space, so there are lots of things you could do