I dont think so. I only have less than 100 hens so small. You cant get around it the shop is selling your produce at the end of the day and the consumer has a contract with the seller by handing over the cash - you cant be clever on this Im afraid if someone who put the money in a box in the shop would still go back to the shop if the eggs where off or poor quality. I sell direct by delivering it works for me. Other option is a honesty box but I wouldnt even consider this.
The process was ok for me he didnt raise any issues but mine are pasture raised high welfare organic so pretty easy. You would need to check your selling price though as I would imagine you'd need to be insured as a producer, labels, date, stamps, transport and paper exercise - selling at £1 isnt going to cover yr costs.