We looked at these a while back and didn’t like the external room since getting there at night or in the rain (rain here?) seems not fun.
It also seems not as safe since it’s not attached to the main house if someone wanted to just break into that room.
However, it would be great as a home office if you have clients visiting or an exercise room (it has it’s own air con) since it’s away and separate so probably just depends on the buyer.
Overall, we liked plan 3 best, but didn’t like how the TV/media area is sorta off center from where you would put a couch.
I’d recommend calling the office to see the lot sizes.