Fitting bathroom fan to pull cord light switch

[bat and ball]

How do I get power from light switch to fan isolater light switch has 2 red wires.

 

[EFLImpudence]

How do I get power from light switch to fan isolater? Light switch has 2 red wires.

You don't. Connect it at the light.

 

[bat and ball]

Can't get to light rose plastic ceiling with spots could I tap into one of the spot cables using wago

 

[EFLImpudence]

Not if you have a timer fan or if the spots happen to be 12V unless you can access the power supply.

 

[Taylortwocities]

@bat and ball even a basic fan needs a switched live and a neutral. A timer fan also needs a permanent live.

Your switch has a permanent live and a switched live. So no neutral. Somewhere up in the ceiling will where everything comes together there will some sort of junction box that will also provide the neutral. Thats where you need to get to.
If you have access to the ceiling void then that's easiest. if not, you nneed to pull down the downlights one at a time and see what you can get at through the 2 inch holes!