you could start off with a simple cottage and then build from that making it your own. you could go into a house modeling mode and in that mode it would tell you how much wood, stone, steel, iron, or any other materials you could think would be necessary, to build a section,wing, or material upgrade for that section. but any ways when you obtain the material needed to get what you want it would go to a count down clock for what you chose. it could take a few days or a few weeks to see what you chose to be complete. you should also be able to deconstruct sections to recycle materials.
you could also build your own furniture and place it where you want while in this mode.
think of all the interesting building designs people could make! the only limit would be your imagination and the amount of land that you bought to put the estate on.