I have been giving a pursue of the approved document F, as opposed to the Planning Portal statement, always ready to correct myself.
Firstly it does state that extraction to the outside is required for kitchens, bathrooms, utility rooms & sanity accommodation (5.5), simples.
As to the control of said ventilation, it slightly less clear (for me). For a room without opening window, an intermittent extraction should have a fifteen minutes overrun. In rooms with no natural light, the fans should be controlled by the operation of the main room light switch (Table 5.2A) (not a direct quote, but all I can be arsed to type).