The diagram for wiring a Timed Fan unit on this site (at https://www.diydoctor.org.uk/projects/t ... n_unit.htm) shows the 3-pole isolation switch fitted BEFORE the Junction Box and Switch but it seems to me that it would be better BETWEEN the Junction Box and the Fan. Is there some reason that it has to go there?
Seems like the Switched Fused Unit would do the trick if you wanted to make the whole circuit (including the on/off Switch) safe and the 3-pole isolation switch could be used just to make the fan safe?