Bathroom dimmer and Extractor fan

[Gavin James]

Is there anyway I can run a dimmer switch in my bathroom with a extractor fan. As I currently have a extractor fan with down light attached with I'm aware cannot run of a dimmer switch but I was thinking would it be possible to replace old extractor fan with down light to a non light humidity sensor fan one, on a separate switch

 

[Chewbacca]

Humidity sensor fans are the work of beelzebub and either fail to run it run for hours in end.