A couple of important questions, starting with units. You mention 7-8kW. That's not the unit usually describing a battery bank. You would normally describe it in terms of kilowatt hours, or kWh. Did you actually mean 7-8kWh? Solar arrays typically could be described by their instantaneous output, which could be measuring in kW. So did you mean a solar array with an output of 7-8kW?
A battery with a capacity of only 7-8kWh would be quite small, and in no way could fully charge an EV battery, which might have at least a 40-50kWh battery. How much you have to charge it is directly proportional to how far you drive it, so to answer the question for a fully depleted battery, you need to charge it with at least 40kWh of power. Are you talking about charging your EV at night solely from the battery, or do you mean during the day, while the sun is shining?
I personally have a 4500W rotating array, and my personal best for production was 25kWh last year while pumping irrigation water, With about 7000W of panels, I'm likely to make the required 40kWh from 8am till 4pm if I could rotate the arrays East to West during the day. Without tracking though, 8kW of panels is not likely to make you 40kWh over the course of the day.
There are three tiers of EV charging...
Level 1: 12A at 120V
Level 2: 20-50A at 240V
Level 3: 480V DC.
That's the US standards. What are the EV standards in the UK? I'll assume you'll be charging with 230VAC?
I'm in California, where my single most important load is irrigation water. On cloudy days, max production of irrigation water is not needed. For you however, you'll need to charge your EV rain or shine. What is the plan going to be for rainy days, which I know are a lot of in the UK, when you just have to drive somewhere?
I hope that gives you a few things to think about before moving forward with this idea.