There were no “assault rifles” then as stated and of course many firearms enthusiasts argue that there is still no such thing, it being an anti-firearm media invented term.
The SAS did not have unique “special to them” firearms. They did have a locally made type of bomb (Lewes Bomb?) designed by one of their members in North Africa for destroying Germanand Italian
aircraft parked on airfields. They made them up locally. A mix of explosive and incendiary material as so recall.
The Welgun was an experimental Britishsub-machine gun and was not used operationally as far as I know. I have handled the one in the Canadian
War Museum’s firearms vault.
The Welrod was a silenced handgun that was made available to SOE and other special units. CWM has one of those on its vault as well.