Kezo i tried to get on an EV tariff with Octopus with my Volvo xc40 plug in hybrid and my granny charger and was told it wasn’t possible without a proper EV charger.
Your car or charger needs to be compatible. If you car isn’t and you use a granny charger, the tariff is not suitable, which is the same problem I’m having with Octopus with the Tucson Phev.
Have you tried Ovo, as the xc40 is compatible?
https://www.ovoenergy.com/electric-cars/charge-anytime-cars-and-chargers
Other than that ou are looking at the likes of Octopus Go, BG, EDF etc, with a 4-5hr cheaper rate overnight tariff.