ok this is what I understand: (applies to England. not sure on rest of UK)
if you sell eggs through a shop or something it gets complicated as you have to have a reg number and stamp your eggs with the number etc.
If you size your eggs there are rules too, and you have to set up as a packing station or something
you cannot pack your eggs in old egg boxes - nor can you supply old egg boxes, but other people can bring old egg boxes to carry them home in
So you can sell your eggs 'from the farm gate' - and that includes your front door, or you can go around delivering them (so long as you dont use old egg boxes or size them)
if you are selling them as 'free range', this is defined by defra
all of the above can be found via defra
http://www.defra.gov.uk/foodrin/poultry/default.htm but you have to dig a little.
but... I have heard that there is a new rule out that if you are sellign eggs, you have to be registered with trading standards.. under their food standards wossit. however i have failed to find the info on it, and even phoned them up and they did not seem to know. its on my to-do list to find out more.... - if anyone knows.. please tell me!!
bartering eggs come under teh same rules as selling apparantly
oh and you cannot give any kitchen scraps to the hens whether yousell the eggs or not.
dont shoot me.. I dont make the rules
hope that helps a little.
i got tired and decided to just eat our eggs, and freeze surplus, but when we get more hens...