All ambitious parents do for their DC what they can within their means. That can be private education, moving into a good catchment, just sitting and supporting them with homework, reading and talking to them etc., helping them find good revision sites- it does not matter what form it takes.
All parents investing time and money in their DC’s education is always a social good and an investment in the next generation of taxpayer. Therefore, civilised Western democracies don’t tax education. It’s the equivalent of R&D in certain businesses. It would limit future growth opportunities and here what this political party has proposed, is lacking in proportionality. The best case scenario of raised revenue does not counterbalance the adverse consequences to the lives of children directly and negatively affected.