It depends how many girls you have, and how many eggs you need. For maximum egg laying, they need to eat almost all layers pellets, with a little oyster shell/grit scattered on the top just to be sure they are getting what they need. Hybrids are more affected by diet, apparently, which is what I have - I believe it doesn't matter so much with pure breeds.
Ours were having loads of scraps from the veg plot but after the hot weather they went off lay. I didn't get them back on until I stopped all treats for a while. Now, they lay best when they only have pellets, and a couple of handfuls of corn just before bed, but they love their treats so much it seems a shame to deprive them. I give nothing until late afternoon, when they have a good handful of mixed greens, and any leftovers. At about an hour before bedtime, they have their corn, which they love.
As the end of a long story, I am going to get a couple more birds (we only have 2) and then there will be so many eggs I won't mind if they don't lay 6/7 each per week like they used to. And if you have more birds you can feed more scraps and still have plenty of eggs. It will be a matter of finding out what works for you and your particular birds.
Basically, they can eat anything you would eat yourself (well, obviously you wouldn't eat cabbage outer leaves or raw bacon rind but they are edible for humans, if not thought delicious by us, is what I mean!) They can't eat raw potato, for instance. Mine love cooked rice, bread, pasta, any meat is a fantastic treat, they eat windfall apples, all leafy greens, carrot peelings, etc.
Good luck, I love my girls, they are extremely addictive. Just don't do what I did and let them out when the cold frame is open, and full of lovely little seedlings just ready to go out!!
