I cant tell you a specific shop, but i managed to get some frozen, shell on edamame from a Korean shop near me in SW London.
If you do a search to see if you have one, nearby, that might be your best bet. Usually to be found in neighbourhoods where there are lots of Koreans living. So aska round if there are such areas near you anywhere.
Short of that, WING YIP might have some, near IKEA at Brent Park.