Found a calculator on Money Saving Expert website. If you get you last gas and electric bill it will have an estimated usage, enter the details and it will calculate how much you will pay from October. It was very accurate with my current monthly bill, £180 a month. It estimates I’ll be paying £324 from October, but do remember we will be getting £64 a month off the bill from the government for 6 months so that should take it to £260, plus my energy saving changes which should reduce it further.
https://www.moneysavingexpert.com/utilities/what-are-the-price-cap-unit-rates-/
Enyaq EV