It maybe worth informing them n the situation with your car.
“The driving assessment may take place in one of our vehicles, please contact us to discuss vehicle requirements i.e. manual/automatic if you need to use our vehicle. Assessments can be carried out in your own vehicle if appropriate and your needs can be discussed upon contacting us.”
https://www.disabilityaction.org/driving-assessment
Looked on youtube for video’s but not really much about as you say!