We are in London, in a 2 up/down with utility room extension. We aren't quite ready to move but need a bit more space. We've had an architect draw up some ideas and basically it will be 3m x 2m extension to make the kitchen, dining room and utility room one big space with a bit more floor space.
I had hoped we'd naturally outgrow our house and move. I never thought / wanted to be here for a long time. But we're just not ready to make a move yet.
I think for the £50,000+ plus more importantly pain-in-the-arse actual building process it's not worth it but dh has seen the drawings with shiny new things and wants to do it 
My suggestion has been to put french doors in the kitchen / diner and take out chimney breasts from this room and the bedroom above and at a push convert loft to a hobby room (can't do loft conversion for proper room).
just wondering what others have done/would do?