Norway already have this kind of solution where a companies on the same land can register to the grid companies, and the production and consumtion within the same messurement intervals is not counted as selling to the grid. This way you can use the public grid for your own "internal" transfer.
It looks like UK, like many other countries, already have grid that can't cope with casual usage and transferring power from farms to users. Adding "renting" of grid sound like it could make it even worse (if possible).
See https://app.electricitymaps.com/map/live/fifteen_minutes