Vote of no-confidence?
Why should the British soldiers die after liberation of the Falklands? How Mrs. Thatcher would argue before the House necessity of such operation?
If you did mean assault on Argentinian territory before taking of the Falklands... Well, what's the point of it? To force Argentinians to relocate garrison of the Islas Malvinas to the mainland? But RN successfully blocked them, and the Army was rightfully confident it could destroy the Argentinian forces in the archipelago. To compel Galtieri to surrender? Very doubtful, taking in the account his precarious internal political standing. To overthrow Argentinian junta? The British weren't in the necessary mood and with necessary resources for the regime-changing war (especially on their own)