I sell my eggs at the farm gate, and they go like hot cakes. I am sure people think I am like a supermarket, and seem to appear at all times of day and night, demanding eggs!!
If you have more than 50 hens you are meant to be registered with Defra. Also, don't size your eggs, as small medium and large or whatever, just sell them as mixed, otherwise you go down the avenue of having to be an egg packing station, and stating what size they are etc.
Legally, egg boxes are only meant to be used once.....yet, your customer can come with their well used egg box and you put the eggs in and thats ok. I think its something to do with contamination etc. but I do not know of anyone using a box only once.
If the eggs look very dirty, I keep them back for us, and with all the rain, some are looking VERY dirty just now.
Also any which have iffy shells, looked cracked etc. Just to be on the safe side. My hens are ex battery hens so will have been vaccinated, otherwise I admit I would worry a bit about salmonella etc I have been selling eggs for years, and have never had any problems.
I am sure you egg selling will be successful.