You will need breakdown recovery. UK Roadside recovery companies like the RAC may recover your EV by giving your battery a quick charge ('EV Boost') via an onboard generator that some vans carry. This charge will provide enough power to allow you to drive to the nearest charging point.
If they do not have this equipment available they will recover your EV to the nearest charging point. If an EV requires recovery it will need to be put on a flat-bed recovery vehicle. Coverage for these type of 'breakdowns' are included in most standard policies.