A small office does not need a contract with a facilities company. It needs someone who comes when the building is empty, knows where things go, and leaves it ready for Monday morning.
Offices are priced by the hour rather than by the room, because two offices of the same size can be very different jobs depending on how many people use them. If the space is small enough to feel more like a home than a workplace, regular cleaning may suit it better, and if it has just been fitted out, that is post construction cleaning first.