No, your double regulation comes from the Shocker's Maxflow which steps it down to the acceptable pressure...no need to put another regulator on it, just screw the tank right into the manifold just like you would a co2 tank. That is precisely what I did with my 114 screw in with my Shocker, as do countless other people.
By the way, DOT bottles are also stamped with the proper UK equivalent, so they're perfectly fine. And 88cu bottles are what I think you call a 1.5 liter or similar over there, so whichever you get will work.