This site has electricity generation for the UK
https://gridwatch.co.uk/ and renewables are basically dead as the wind has stopped blowing and due to it being winter solar is also dead and both have been for the last 39 hours.
How much battery capacity and how big an area of land would be needed to power the UK for that length of time using the 35.5 to 38.5GW's average electricity usage?
Because currently we are just burning lots of natural gas with some coal and biomass.
This is with the UK having 25GW of installed capacity for wind power and 14GW of solar.
We need fusion to become usable a lot faster than it is going to be.