"Home education itself is not a welfare issue"
As is stated VERY CLEARLY in the recently issued guidlines to Local Authorities on Home Education
link
You might find this useful to read AbbeyA, since it outlines the legal position of HE in the UK. You will notice not only the welfare aspects being addressed, but also very clear instructions to LAs.
Bottom line: parents, NOT the State, are responsible for the education of their children. If we choose to exercise that responsibility by educating our children ourselves then, in law, the State has to have valid grounds for believing that an education is not being provided.
If some of the school-lovers around here want to change the law so that the State is responsible for the education of all children, with intrusive monitoring of HE children, then the State is going to need to brace itself, as are schools and the teachers within them, for a deluge of lawsuits from the people who leave school dissatisfied with the education they received there (functional illiteracy, anyone? What's the statistic? I heard 1 in 6 school leavers but I can't believe it's that high, I mean, that would be outrageous).