children should have autonomy over their own bodies ... overriding parental lack of consent to get immunisations, etc

This is interesting. Everything you've said I agree with, but I wonder if that's just because I agree with those things.

For example, I don't believe that children should be able to override their parents' wishes and skip immunisations. And I'm not sure at what age it is appropriate to allow a child to opt to be circumcised for decorative or religious reasons.