I contacted everybody from The Department for Environmental Food and Rural Affairs to a Horticultural Marketing inspector at the Rural Payments Agency who wernt as helpful as I would of liked. One piece of interesting information I did find out was that supermarkets all have their own individual standards.
This is when I came across a really important scheme that Waitrose is involved in, called the Small Producers Charter. Who aim to sell locally produced food in the supermarkets. After researching the requirements in supplying locally produced food in Waitrose, I am confident that the children would be able to grow their own food (under supervision) and supply to the supermarkets under this scheme.