In the UK, you have to inform them of any medical condition you have - regardless of whether it means you can or can't drive. It was decided for different reasons, that I would never be able to legally drive; so never bothered trying.
If you suffer from autism, telling DVLA will depend on whether your condition affects your driving.
If autism does not affect your driving
If autism does not affect your driving - you do not need to tell DVLA.
If autism affects your driving
If autism affects your driving - you will need to tell DVLA.
To tell DVLA please download the medical questionnaire 'M1' and send it to DVLA.