The only timer I have seen is the switch that when pressed turns on the lights for a set period of time.
As Dillb said you'd need to wire in a separate timer somewhere along the line or you could use a smart wifi socket if the fan only needs to be switched automatically, I used the following for the Christmas tree lights and set up a schedule, can be overridden if required.
Thanks.
I’ve found this (link below) which allows me to turn things on and off via my phone, it can also be programmed to come on when the temperature gets to a set point.
It looks like I’ll also be setting up my central heating to use this as well
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