I sent off for the stuff last year but never applied in the end. If you listen to Hugh Fearnly Wittingstall the EA will beg you to cure them of their crayfish armageddon. The reality is somewhat different.
You need to apply for a license to trap crayfish, it’s different from a rod and line license. There are a lot of considerations. Firstly, there’s a bit of a catch 22: They won’t let you trap in waters where there are white-clawed crayfish, and they won’t tell you what these are. They ask you to give details of the stretch of water you intend to trap on, including the owner, then they’ll tell you if you’re allowed to trap there. Your traps need to conform to their spec for not catching water voles and otters, and if you intend to transport live crayfish you need a separate licence to “keep” them. So if you want to purge their digestive tract of mud and sh1te before you eat it then you need the same licence as a commercial crayfish farmer.
Basically they want the waters rid of crayfish, but they don’t want merry foraging fearnly wittingstall types taking out all the big mature specimens to eat and leaving the smaller ones to proliferate.
I can email you the info pack/licence application if you want.