The problem is it's difficult to improve things for the disadvantaged without inconveniencing the advantaged, and possibly meaning that some children don't have access to the better opportunities that aspirational parents want for them. So I doubt there will be much political will to change things.
One thing I'd say is a major problem in the English system is the idea of parents chosing a school - this means that parents who are able to will always get their child into a higher-achieving school, leaving those whose parents don't understand the system, or aren't interested, or don't have much in the way of travel options in the "sink schools", which then get a bad reputation, and spiral downwards in terms of achievement/reputation/morale.
Up here there is still much more of an assumption that you will send your child to their catchment school, and that the catchment school will have a place for them. I'm not saying that's perfect but it becomes the exception to pick a different schol, not something that parents obsess over.
I'd also increase provision for out-of-hours care, including homework clubs, so that those who would like to do better but don't have a good home environment or parents who can help will have an opportunity not to fall behind.
Oh and an option on properly-valued vocational/practical courses from 14 for those who are just not academic. Make sure they have literacy and numeracy skills for day-to-day life, then let them learn something more practical. But don't push them into that just because of where they live or what their parents do, give them a genuine chance to shine academically first.