The UK grid is on track to eventually becoming fossil free, although there will likely be a long 'tail' period where natural gas backup plants still operate during periods of unusually high demand and/or restricted supply.

2020 will very likely be the first year that renewables overtake fossil fuels in total electricity generated.

Here's a satisfying video of UK coal-fired power plants being demolished: https://www.bbc.co.uk/news/av/world-europe-52985841