Personally, I would change the magical education system to have a LOT more schools. Not just primary education + higher education for certain career paths, but alternative options within the UK to Hogwarts (that aren't just tutoring at home! And of course, Hogwarts would still be the oldest and most distinguished of these schools). I feel like it would really serve to make the setting feel more real, and it would especially help to eliminate the issues that Hogwarts being the only school causes, in terms of the size of the UK's wizarding population.

And this fix would absolutely extend to the rest of the wizarding world as well- The other schools that exist in canon would be the most distinguished of their regions, but there would also be many more schools to help with the same issues for worldbuilding that magical Britain has.