I was also able to make space to actually move around and be seated inside the house by carrying my wintering-over potted plants to the greenhouse. I'm thinking the man of the house is glad he bought me the greenhouse for that reason also.
9’ x 9’ will work, any smaller allows for too many changes with the outside temps.
Maybe when you move to your land, he will extend it, by then you will want it extended.
LOL, start your wall of water bottles on the south or west for the most heat, south being desirable and west is the hot sun.
Don’t forget to plant the cabbage plants for the winter and a lot of the other vegs will do well over the winter and grow year round, tomatoes will grow 2 or 3 years in a greenhouse.
I prefer my greenhouse to be attached to the house, in fact it has been said that I might be happier, if I lived in the greenhouse and didn’t have to mess with a house.
It is great fun to wander into the greenhouse and check things out, when you want, with out having to reach for outdoor clothes, coats, etc.
Check out solar greenhouses for great tips on things you can do, the hippies did wonders with developing solar survival green houses. Complete with fish for food and rabbits in them.