Do the switches for lights and /or fans for an ensuite bathroom have to be installed inside the bathroom or can the be outside i.e on the bedroom wall adjacent to the bathroom door

The standard and ideal place is inside the bathroom.

do the switches for lights and /or fans for an ensuite bathroom have to be installed inside the bathroom or can the be outside i.e on the bedroom wall adjacent to the bathroom door
In or out! You choose.

To add: Doesn't hurt to check with the authority having jurisdiction. I've heard of stranger things: some areas may require it be on the outside??