I grew up in Scandinavia in the 1970s, where most kids went to kindergarden or just knocked around at home with a SAHPs or grandparents until the age of 7. We all went to neighbourhood state school because there weren't any private ones. There was no pressure to move to get into the 'right' school, no hectic traffic-ridden school run as we all went to a local school which was walkable, no uniforms and no grades or exams until we were 13. I loved it, and would prefer my kids to experience something similar.
Every single parent I've met in the UK has concerns about their children's schooling, especially about starting them at 3 or 4. And it seems many teachers feel the same way - have a look (and listen) here: Call to start school at age six
So if you were PM for a day or two in charge of the education system, what would you change, if anything?