You won’t be using 80kW a week to charge, even fully flat you’d only get about 72kW into the larger batteries. Usually most charge from 20 to 80% so only around 50kW.
One thing to take advantage of (with B Gas or Octopus) is if you can shift your heavy domestic use, washing machine, dish washer, tumble dryer etc. to night time use you also get them at the cheaper rate 🙂
My use last month was 280kWh, 245 of that was charging the car, the rest was domestic use.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!