I would advise you to get a free 30 minute consultaion with a solicitor or if you legal aid with your home insurance use them.
There infrastructure grants available to landlords but, typically would likely be for communal chargers rather than your own. Unfortunately there is no legal law “yet” suggesting Freeholders/Landlords must install or allow you to install a charger on their property.
There is also a £350 chargepoint grant for renters and flat owners but require the landlords permission to install one.
Have you told the freeholders, that you will meet the full costs, which I can assure won’t be cheap and way out of the scope of a standard install offered by Motability.
Its also worth speaking with your MP.