What the Brits needed was not GPS for their Air Force, they needed more common sense than to send more than 250 men to their deaths over a tiny dot in the middle of nowhere.
possibly a far larger amount of damage to the Port Stanley Airfield then in OTL. The real question is what if the Argentines also had it?
#Aircraft navigation prior to 1993 is something I don't know much about but it seams resonable to assume they got at least decent navigation systems.