Confused about switching for a electric shower extractor fan.

Don't the regs also specify switch in the power feed to the shower unit? Normally pull cord jobbie. You can pick up a switched (and permenant live for any run on) in that switch. Both of these would need to go through individual FCU's to protect the fan wiring and a fan switch to ensure proper isloation when working on the fan.

I can also turn my lights on separately when I need to with the "other switch".

I have decided after much thought, to call the "other switch" the light switch.

I have two! I call them the switch for the main lights and the switch for the recess lights. Why, I leave as an exercise for the reader. They are quite near each other, but it is far from the end of the world if one operates the wrong one(s).