hi @gazzagaz, do you have a 3 phase power supply at home. If not, you can only have a 7KW charger. So check your mains for feasibility of having a 22kw charger. If you dont have 3 phase supply, DNOs can charge anywhere between £2-5K for upgrade, which you will have to factor into any cost saving.
If you already have 3 phase supply, the question is whether you drive more than 150-200miles each day or you cant charge at night? if not, cheap off peak charging with EON or Octopus will give 50kwh per night, which is good enough for 150 miles.
If you do drive more than that often, then it is the cost of public charging for extra vs. cable and 22kw charger installation costs. Motability only give Ohme which is 7KW. If you need 22kw, think it will be at your own cost.