How about an SSN and MLRS, and more than a token fig leaf of air cover?
The best way to keep the Falkland Islands is to avoid losing them in the first place. I seem to remember (from reading about it - I'm not that old!) that Singapore was considered an impenetrable fortress that couldn't be taken, especially by a 'minor nation' with 'inferior kit'. How did that work out again?
Over-egging the defence of the Falklands, at least until the situation reference oil, etc, is clarified, can have no real impact except for a relatively minor cost implication. Under defending the Falklands however, could have catastrophic consequences.....