How we see the education provision depends on what sort of economy and, therefore, politics you support. There are three choices, free market economy, mixed economy or command economy.
Those who want a command economy, banning private education, private health, etc., need a far-left socialist government to bring that about.
Those who think people should go without if they can't pay will back the current neo-liberal government. This government is pushing us ever closer to a free market economy with minimal state support for anything.
In mixed economies, based on the capitalist system, most decisions are made by the market. Additionally, under this system, some areas, such as health, education, national defence and welfare, road building, school and hospital construction, the supply of medicines in hospitals, etc., are state-run.
After the war, we moved to a mixed economy. It is what most governments have said they would maintain. However, this current government has made it clear that because of its ideology, it will drive us away from the mixed economy towards a free market economy.
I can see no proof that taking choices away from some, as you would in a command economy, improves the standard of state-run services. There is no evidence that those currently choosing to pay would care more if they were not allowed to make choices outside the state system. We see this argument repeated often, but with no proof, no example, offered.
Our current government stood on a platform of moving to a free market. That is why it is draining support from the part of the mixed economy previously funded by the state. They told us this is what they would do; it is what they are doing.