Hi,
I cover this topic in 'Working 5 to 9' - if you have the book, all you need is on pages 74 - 77 but in summary ...

Your kitchen should be registered as health and safety checked by your local council. Contact them to arrange a visit - you can find details at www.direct.gov.uk

And it's also advisable to take a health and safety/food hygiene course.

If you're displaying at Farmers Markets and the like, you will need insurance - and that's covered at www.farmersmarkets.net

Best wishes
Emma