Between Brexit and the aging population, I don't think joining the rest of the world in poisoning the atmosphere for the future faster is going to improve the UK's situation. There are much, much bigger fish to fry than energy policy for improvement-per-unit-effort.

The UK relies heavily on tourism. Tourism is disrupted by global instability. Climate change and fossil-fuel-catalyzed wars cultivate global instability. And the UK doesn't have the land or people to compete on the global stage in manufacturing exports (not that they do bad work, just that the scale doesn't exactly pan out. Not unless people are really keen on telling the tale of two cities again).

Best policy is likely to focus on domestic affairs (how to keep the country stable and solvent as the population shifts towards more and more retirees) and maybe look into rejoining that massive free-trade sector right down the block that the country so short-sightedly left a short time ago, since it'd really open up the tourism and trade markets.