Chef Geri being that you are in the UK your regs are likely different then ours. There currently is no legislation or regulations concerning lighting levels in commercial kitchens, there may be in correctional institutions but not ion my experience. What we have are recommendations as to proper lighting levels per task. The only actual rules are regarding electricity, in which case there are definitely regulations one has to follow by law. As far as lighting goes, generally you want a relatively high foot candle level in the 30+ range. You want enough illumination to make the work environment safe. Consideration will go more towards the type of light fixture you use. If you are in a food prep area you would want a fixture with a plastic or arcylic lens to avoid any glass breakage. In a walk-in you must use a jelly jar type with a cage. Dish areas you need moisture proof and in bakery areas with high flour content dust proof and explostion proof fixtures are recommended. These items are usually spec'd and recommended by the Electrical Engineer or Lighting designer. Occasionally by the Architect or owner.
You can get further information from IESNA, or the UK equivalent. Get in touch with any Electrical or Consulting Engineer for more specifics.