I have a teaching background and so do many other home educating parents.
I don't think that I could teach beyond key stage 2 outside of my subject areas.
At key stage one and two, it's a bit different because children vary so widely in their ability levels that it's a luxury to go at the child's pace. I realise I have an edge in terms of my background but I also make use of the resources available to schools, the resources specifically made for the home ed community and tutors. My children did return to school with advanced study skills, a real love for learning because it had all been tailored to their interests and they have been in the top sets ever since.
One of my children was in the bottom set for everything when we removed her from school and was very unhappy. She had additional needs that were not acknowledged. We were later told that this was due to a lack of funding, not, as we'd been told at the time, a belief that there was no need for special provision.
I worked my ass off to make it fun, effective and cover all the bases. Their formal learning time was relatively brief because one can get so much more done in a one to one setting. They still spend most of their lives doing fuck knows what building dams and dens and sea glass fortresses with other feral children. There was at least one birthday every week in our community so there was always cake. They played with everyone regardless of age or gender. They also did all the usual things like swimming and surf school but more cheaply because it was during school hours. A lot of places like zoos, museums and theme parks will open during school hours to home ed groups and many educational resources are available at a vastly reduced price to home ed families subscribing or attending as a group. When my son entered school he became instantly popular with everyone because he was willing to play with little girls from other classes and give his time to everyone in a way that other little boys didn't. He also didn't see the point of wasting time in lessons because why would you, this is your learning so you can grow up and do stuff.
I did sometimes think what the hell was I doing but my daughter went back to school after four years at home and said, "Everything is so easy. When will I learn something new?" She continued to say this until the spring term of big school. Not bad for a kid who couldn't read in the school system at age 8.