The most effective government intervention is eugenic policies to raise the average IQ. IQ is the "God metric", not GDP. IQ is correlated with almost everything good.
It is impossible and unnecessary to predict the exact consequences of increasing IQ. Starting from our present condition, the consequences of small increases would only be good. Society is an emergent property of the people that comprise it, more complicated and dynamic than the ants nest which is at some level specified in the ant genome.
The societies that emerge from high IQ populations are better than those of a low IQ populations, as we can see by looking around the world. Give the United Kingdom a higher average IQ and it will become even better.
Increasing IQ is easier than trying to figure out how to improve the education system or the NHS. Give people higher IQs and they will do it themselves. (They will also be cleverer and healthier already!)