World population is already falling. Most countries in the world now have birthrates around or below replacement rate. Any increase in population is driven by longevity. But we will soon reach a stable figure for longevity that is unlikely to rise substantially and world population will start to drop.
In the meanwhile it is possible in the long term to support a prosperous world population using renewable energy. However until we reach that stage, we need to use other forms of energy generation to tide us over. This means nuclear and gas.
Of course, Nirvana is fusion. It will come - but probably not for at least another 50 years.
What this country needs, and which is completely possible, is an insulation programme similar to the great engineering achievement which was the conversion of Britain to natural gas.
A systematic programme of teams of operatives, assessing homes, installing appropriate insulation and draft proofing. Just as with the natural gas conversion scheme there will be non-standard properties, Listed buildings, and other buildings that cause problems and these may take longer to make energy efficient and for some this will be impossible. So it was back in the 1960s.
It will be far more effective in reducing home heating bills than all the 'bread and circuses' being provided by this current government, that addresses the immediate problem but does nothing to provide a long term solution.