Ireland had better points difference, so think we would have needed to win by more than 7 and deny them the bonus point (and score four tries if they did)
But yes finishing top of group means the PD v France wouldn't have mattered.
Edit.. Head to head per below first tie breaker, so a win would almost have guaranteed progression.
But we would have needed to say avoid a 21-20 win (3 tries to 4) which would have left Ireland on 10 points and us on 9.