Julian , I worked in Health and safety for council for 10 years.
Your new employee would be classed as a young worker (up to 18 years old).
So they have to be treated differently to normal workers.
You would need extra risk assessments,not to allow them to work on their own, and would need to detail training needs and requirements.
H+S exec website will give you info on young workers.
They say because they are young they are not competent mentally or physically.
Good Luck Robbie - clearshine - Harrogate