Sorry if it sounds like a bunch of silly questions but I can't get my head around education over here. I also can't get my head around people struggling to pay for school fees - will this change because of crappy schools

I love living in Greenwich and the diversity of it but I am worried about the standard of education. I'm not personally into fee-paying schools, having been educated in NZ myself. I don't mind paying fees for extra tuition, outside activities - music / drama and so on but I am not that keen on private schools.
More importantly where are the good secondary schools in Greenwich?
Would John Roan be a good secondary school?
Also does schooling over here really determine whether they can go to University, by this I mean are some of the local Greenwich schools so poor it would limit the chances of students going to top universities even if they were bright and dedicated?
OK I have 1.5 year old boy, so I am thinking long term but I want to know what people think about schools in East Greenwich:
1)Millenium School
2)Meridian School
3)St Josephs
4)Christchurch School (I think that is what it is called?
Are they ok primary schools? Are they good?
I know it sounds really silly to ask now but what age do children start school? I see kids in really funny uniforms but they look about 3 - is this usual??