$1:
I could be mistaken but from everything I've read and seen (including news footage of British troops walking down a road in Stanley carrying FNs) the British troops used FNs modified to fire 3 shot bursts and the Argentines had full auto FNs. There were even instances of the Brits using captured Argentine rifles instead of their own because they were full auto. The Argentines definately did not use ARs. "The Argentine Armed Forces officially adopted the FN FAL in 1955, but the first FN made examples did not arrive in Argentina until the autumn of 1958. Subsequently, in 1960, licensed production of FALs began and continued until the mid to late 1990s, when production ceased."
You are mistaken. Regular UK infantry of the era carried the SLR, which is a modified version of the FN that was produced in the UK. It was and remains a single shot rifle. No auto setting at all.
The SAS and SBS to a man used M-16's (or variants thereof). I never saw a Hooligan or a SB or SF Booty with an SLR.