Ban private schools, ban grammar schools, ban the very good state schools the middle class swarm and drive the house prices around, ban private tutors, ban foreign students taking all these new places and take people away from their parents at birth and give them randomly assigned government foster parents.
Although in all seriousness having grew up in a **** hole, the main issues are abusive and/or unsupportive parents who don't see the point in education and hence never encourage their children to try, and only really having 1 chance at it. E.g. if you're born into the lower class and have messed up a year that's it your parents are going to pressure you to get a job or will just kick you out and you need one to avoid being homeless. Vs middle class people I knew growing up whose parents just sent them back to resit over and over again until they passed.
Best way of solving this would be too tell the teachers who work at schools in **** holes to be much more encouraging instead of passively looking down on their students as future benefits leech's, criminals etc. I had one teacher at secondary who was really like that and students did much better in his classes because they actually tried.