Finnis would disagree with natural law since he believes that in order to decide right from wrong, we must use our conscience.
While conscience is the voice of God and natural law was established by God, conscience takes the context of the situation into consideration, which is not the case for natural law.
Aquinas however, does support the idea of Eudaimonia. However, Aquinas believes that Eudaimonia is impossible to achieve while alive.
However, Finnis would disagree since Finnis believes that you don’t have to go to heaven to have successfully fulfilled Eudaimonia