With a suitable home Charger (Ohme) or Vehicle – Intelligent Octopus Go will give you 6 hours of off peak (11:30 pm to 05:30 am) electricity at 7p per Kilowatt Hour (£0.07 / kWh).
Looking at EV Database the Peugeot e-3008 you suggest will average 235 miles from it’s 73kWh battery which equates to 3.2 miles per kWh.
Therefore a full battery charge will cost approximately £5.11 (not including charging losses). If you ONLY charge at home then 15000 miles would cost approximately £328 (15000/3.2×0.07) per year. If you charge away from home you can expect to pay anything from 35p to 90p per kWh.
So roughly speaking your yearly fuel bill for an EV (charged at home off peak) would be less than you currently pay per month in fuel!!