I do! We built it off the back of the house when we bought it so many years ago. It's not huge, but a useful extra living room (the house is more like a cottage, so had only two rooms downstairs when it was built originally). The estate agent told us that the house had been on the market for such a long time because, although it has four bedrooms upstairs, including the attic room, no families wanted it because there was only one living room. So, we thought it might make it easier to sell on if we added the extra room.
So it's a proper foundationed room, with insulation and tall windows and a glass roof. It was great when it was built, and I do still like it, but it faces west. With the summers getting hotter, in retrospect, I wouldn't have agreed to the glass roof!
ps. It's only about 3mx 3.5m, so not one of those massive things with plants hanging everywhere that you see in magazines!