To deal with the original question (rather than all of the side issues which have been raised here), a service provider has to ensure that a disabled person does not 'suffer detriment', in comparison with others, when seeking to use a relevant service. Where necessary, a service provider is required to make 'reasonable adjustments' in order to ensure that such 'detriment' doesn't occur. [Equality Act 2010].
So, for example, it might be argued that some disabled people wouldn't be able to use a multi-storey car park if the only available spaces were situated well away from the lifts. In such circumstances the car park operator could be required to make the 'reasonable adjustment' of designating spaces on the ground floor, or close to the lifts on other floors, as being solely for the use of disabled people. It might also be necessary to make those spaces wider than usual, so that wheelchair users aren't effectively barred from using the car park through being unable to get out of their cars.
However the car park operator doesn't have to provide those spaces for free, since a disabled person wouldn't 'suffer detriment' through having to pay the same amount as everyone else does.