Personally I'd like an English parliament in Birmingham and a small federal overlord body in Westminster split between the four home nations.
If you want regional laws then England is too big, much bigger than the other 3. Or the others are too small. The home nations are an historical curiosity and not a sensible foundation for modern government.
A Federation of Regions of England would be fairer,
but London always ends up the most economically important region,
and some regions will just never have the population to grow GDP close to London,
or a south east region.
How does the federal system in Germany maintain a semblance of democracy?
If you want regional laws then England is too big, much bigger than the other 3. Or the others are too small. The home nations are an historical curiosity and not a sensible foundation for modern government.