Ya best off seeing crab boats that drop there pots well off , they get them the size of ya fist

used to get the from a skipper in burnmouth , got to keep them in water or they croke , to get them out the shell use a kitchen blow torch , they jump out when you heat the shell
Ya can buy frozen ones but I've never tried them , fresh ones are the dogs off the coast just hard to get a hold of , good luck mate