To fit an Ohme unit, have own electrician install, would cost £1200…£500 for ground work, £550 for Ohme unit and £150 for extra cost for electrician to wire up Ohme (to inc. small consumer unit/rcb etc).
I ended up doing something similar in 2021, ignoring the silly Motability/BP and installing my own unit for £550. I fitted 43m of 6mm cable as I had the electrician run two, one for the charger and one for future proofing for another charger, to save cost of running another cable later. 50m Cable was about £70 at trade price. Charger was £300, installer was £250, inc. cable, rcb and a lot of swearing up in my roof space…
In life, it's not who you know that's important, it's how your wife found out.