As long as the owner says OK, no problem. FCU is a fused connection unit

can also have a switch and/or light.
It does surprise me, we need to register any additions to electrics in kitchens (In Wales no England) but not to remove.
There are rules on ventilation,
Part F of building regulations. See page 5, also page 8, and this
does seem to say must be an extractor, you can hunt through the document the same as me. It is for new builds, but it would depend on when your flat was new, and what regulations there were back then.
We are told we must have an extractor in the bathroom, mine has never worked since moving in, and because the shower once the door is closed only has a small gap above the door into the rest of the room, never found we needed a fan.
The kitchen does have a hood with ducting to the outside, but with an induction hob, the kitchen does not get super hot or humid, if cooking with gas, then would be very different, burning gas produced water. But the regulations do not say different extraction rates needed for gas and electric.
The big question is who would know? For me not to repair the shower extractor is very different to ripping it out. And when we were looking to put my mother in an OAP home, and rent out her house to pay for it, we realised how much work was needed to bring it up to scratch, so we sold it, as it turned out after her death, but during my life I have worked away a lot, and often considered renting out our home.
To put it all back again is a real pain.