For working from home and working on the home systems the Home Office is an important room. A small, dark room in a left-over corner of the house won’t cut it.
A room on the ground floor is an option. A room on the first floor would seem a waste of a bedroom (though using an area of a large landing might be a possibility). Something on the second floor might well be the best idea. Having a good view is definitely preferable.
Also need a “server room” to house some of the back-office IT systems. These can be noisy and benefit from a clean environment with a relatively stable temperature. Assume about 300W of heat generation so should include an extract vent into the MVHR system (and a dedicated inlet vent?).