Coming late to this thread, only read first and last page, here is my tuppenceworth.
The sooner schools accept that parents won't or can't help at home, the better. Young children have a long school day as it is and all their learning should come from school within the school day and older children should be able to do their homework at school and have staff to help them if necessary. My dd's school has this but only for selected children. It works very well.
The disadvantaged are suffering from social segregation and that has created a massive imbalance in schools. This can be addressed by ensuring lottery placements where schools are oversubscribed.
Disadvantaged children will benefit from having vocational courses valued as highly as academic courses. A decent minimum wage based on qualifications will help students appreciate that their courses have value and that they are valued. Why do a 'business management' course when all it gets you is a job in McD's for the same wage as the completely unskilled untrained person?
All of this will hurt the advantaged, their house prices will go down, they will have to pay tradespeople more money, they will not gain an advantage by spending £££s on private tutors, because all children will have the equivalent, for free, in school.