In the US, sans certain specified professions, federal and most state laws effectively exempt properly self-employed children or children working in their parents' business from most restrictions. Do such exemptions exist in the UK?
No, I don't think so. The basic rule is you can work part-time from 13, and then full-time from 16 (soon to be 18 - basically, the minimum school age). It doesn't matter what the form of employment is, they're generic rules, and largely about ensuring children attend school.
In the US, sans certain specified professions, federal and most state laws effectively exempt properly self-employed children or children working in their parents' business from most restrictions. Do such exemptions exist in the UK?