unless raise in temperature in kitchen required sounds like a b&b if that many or flatsWhy so many? Is this a B&B. Most houses tend to have 2 or 3 smoke alarms - generally hallway and landings. None in the kitchen.
It’s just a normal house, I was reading up on it and they recommend one in virtually every room , except bathrooms. I may just put linked ones on each landing , and heat ones in the garage and boiler room.