I insured my Tesla just fine. A bog standard £42,000 Tesla Model 3 has the equivalent 0-60 of a mid-level sports car. You can't expect insurance to be cheap.
The biggest gain with an EV is unlike a mid-level sports car you will pay £2 to fill it up and nothing whatsoever for servicing and road tax. My last BMW was £1,000 per year just for road tax and servicing and then £60 a fill up. The insurance was around the same.
The cost of ownership so far for me has been much lower. We'll see what Labour do over the coming years if we want to test whether governments are serious about EV's or whether climate change is actually just an opportunity for punitive taxation. If they bring in a new expensive road tax for EV's then there's very little point in getting one.