I agree with steve2's comments with regard to you already having said 'Goodbye'.
Apparently, your father hasn't asked to see you before he departs and others in your past family haven't seen any reason to inform you otherwise, I expect they would have informed you directly.
It appears none have had any relationship with you and probably have never met your partner or children.
I also agree with Wasanelder Once comments about writing a note, but only if that would be beneficial for you. Even if it is not actually sent, sometimes writing down your thoughts and feelings can be therapeutic. I think seeing your father in person could stir-up emotions that were long ago put in storage.
While expressing forgiveness sounds as a great thing, if he doesn't feel bad for how things turned-out, he may not be accepting of forgiveness, especially if he thinks he hasn't done anything wrong. You could be left again reliving the emotions you had experienced 20 years ago.
I believe the desire to forgive is more of wanting to 'let go' and no longer hold things against him, having come to accept that nothing will change.
Feelings held in storage are a heavy emotional load and serve little benefit so letting go and acceptance lightens the load on you and provides a type of fresh start and outlook. That is a personal realization within yourself and does not require expressing that decision to him.
Ultimately, think about what is best for you and your immediate family.