Hmmm, as Magius said, that is a freakin' 'uge 'ouse!.
Unless you are going with the 1.5" grid, then it sort of snaps into focus. (Part of why I don't use 1.5"....)
something that you may want to consider - a house that grew over time, a central house, then some wings, added one at a time. TLX is very well suited for this kind of build. And since it is so very, very modular you can change your design as you go.
I am from New England, an awful lot of older houses are very narrow - call it one tile wide. The number one source of light, into the early Twentieth Century, was the window (a device that allows you to see through walls!). You do not want to be too far from a window, so buildings were often several narrow sections attached together. (Even palaces - take a look at Buckingham or Versailles.) An alternative is what was called a light well - an exclusion running through the building, allowing light and air. Think in terms of letters - T, L, H, O, and B shapes - strips of three tiles each, connected with a tiles
A big building, such as you are describing was most likely a 'B' - two strips of five tiles, connected by three single tiles. Thirteen tiles per floor. Twenty six for two floors, but you do not have to have every section the same height. I might make one of the five tile sections three stories tall, thirty one tiles just for the floors. Add two tiles to the ground floor for the bottom of the light wells, but these will most likely not be Thoumont tiles.
This design allows for two light wells, which can also contain gardens, most likely a flower garden for the owner's family, and a kitchen garden for truck and herbs. For southern European examples, look at Italianate Palazzos. A design that has been used since Roman times.
Going inside... gets more complicated. Remember - the hallways will also be lit by windows, so choices are dim central corridors, lit by windows at the end, or well lit corridors that follow a wall. For a private home it is likely to be a combination - well lit for the owner's area, mean dark corridors for the servants.
My advice in that regard is to use the TLX planner - it will give a good idea of how many walls you are going to need.
The Auld Grump, if you thought that this was wordy, you should have heard me going on about 'Boring Brick Buildings' and insurance factories....