Whether it's a technical or legal prohibition, having no insurance means you cannot drive. (Or, rather, you can, but it's a BAD IDEA. Rather like how you can drive without tires but it's a BAD IDEA.)
Yes, in my country auto-insurance is legally required in order to pay roadtax for the car, which is mandatory to operate the vehicle on public road. It's renewed yearly, and cost a lot more than roadtax. It help pay for the damage you caused, while the more expensive plan cover your own vehicle.
UK is probably the same case because we follow a lot of the colonialist law book.