Just found this page that says you have to ask permission for the extras!
https://www.motability.co.uk/contact/faqs/can-i-add-optional-extras-to-my-car
Quote
”
Can I add optional extras to my car?
You can add optional extras to your vehicle, but you will need to ask us for authorisation first. You will be responsible for any costs associated with these and please note that you will not be reimbursed when you return the car, even if your lease ends early.
For more information on modifications, visit the Adaptations and modifications page .”