I have bought a Dyson hot+cool Formaldehyde Fan Heater to use as I read a fan can help reduce SIDS I have been using it on the fan cool setting but coming into winter wondering if I use the lowest heat setting if it will have the same effect if it’s blowing warm air ? Or should I keep using the cool fan setting and move the bassinet further away so it’s not too cold ?

Red Nose does not recommend that a baby’s sleep room needs to be kept at a specific temperature, but recommends dressing baby according to the room temperature.
https://rednose.org.au/article/how-to-dress-baby-for-sleep

The main concern when using a portable fan for a baby is one of safety. Ensure there is no way a baby can access the fan…...do not have it too close to the baby’s sleep environment.

If your concern is related to overheating, Red Nose has the following information.
It is not necessary to monitor the room temperature or to leave the heating or cooling on all night, as long as the baby is dressed appropriately for the room temperature.
Some studies on the use of fans has reported a reduction in risk of SUDI, but this was mostly noted in unsafe sleeping environments (eg when a baby is placed prone to sleep)
Red Nose has not included use of a fan as part of Safe Sleep Recommendations.
“To date, there is no evidence to show that maintaining a specific room temperature prevents SUDI and that thermal factors are implicated in SIDS as long as:

The baby is placed to sleep on the back
The baby is dressed appropriately for the room temperature (not over or under dressed)
The baby’s head and face remain uncovered
Baby is not exposed to smoke”
https://rednose.com.au/article/room-temperature