Thanks guys - i have just found this site helpful:
www.employment-solicitors.co.uk/ChildemployEmploying children and young persons
A ‘child’ is defined as anyone younger than the minimum school leaving age. 'Young persons’ are defined as anyone over school leaving age but under 18. Young persons are protected by the terms of a European Directive on the Protection of Young People at work, which were implemented into UK legislation within the Working Time Regulations.
No child may be employed:
If under the age of 12 years;
During school hours;
Before 7 am or after 7 pm;
For more than two hours on any day on which he or she is required to attend school;
For more than two hours on a Sunday;
In any industrial undertaking; or
Where they are likely to suffer injury from lifting carrying or moving heavy items,
A local education authority has powers to supervise the employment of school children in its area and may require particulars about a child's employment. It may prohibit or restrict employment if it feels that the employment is unsuitable even if not unlawful. A person who wishes to employ a child must obtain a permit from the local education authority.