Cut away the cable locking mechanism if you are not worried about people unplugging you:
https://www.speakev.com/threads/anti-locking-a-type-2-cable.142659/#post-2690415
Looking at grid, there is ALWAYS surplus electricity overnight: https://grid.iamkate.com/ So the answer is yes, there will always be cheaper off-peak deals.
I'm at price cap on E7 with 13p off peak and 20p other times. Regional average price is ~19p.
How could they implement taxation of home charging. Have a think, how do you police that?
Only way to tax home charging is to tax all home electric usage, which wouldn't happen until home gas heating has become abnormal or more tax is put on gas so that electricity heating becomes price competitive pushing towards zero combustion home heating.
Rapid charging tax is totally feasible, and/or per-mile tax for all cars (meaning home charged EV is still cheaper to run).
Knowing I can plug-in at both ends, I'd simply drive like the wind, often faster than my diesel. Because the proportional cost increase for the cheaper EV miles mean absolute cost increase is minuscule.
Even better when workplace charger is free.