I've been to both State School and Private School
Sure, it is unfair if you cannot afford Private School. Parents pay for Private School for the opportunities it provides because State Schools cannot. Parents pay for the facilities, the quality of teaching, the extracurricular activities and a multitude of different things.
I'm currently at a State-Funded College. The quality of teaching is horrendous and its appauling. But you cannot change that, because the government pays, not you.
I wish I was still at Private School because of this. Your parents also pay so you're more on a 1-1 level with your teachers in terms of educating. My classes had 15-20 people in them each, sometimes not even that.
State schools, funded by the government, cram as much people as possible into one class. You receive less attention.
Private Schools bring out better educated people for a reason, but abolishing them does nothing but put even more students into the private sector.
Everything you pay for, you pay more for better quality. You can't afford it? You'll receive the quality you can afford. My family were working class irish immigrants. My father worked as hard as possible to afford this opportunity for myself, and he sacrificed a lot of things to make a better life for himself and my family.