What I have to offer may not be technically correct theology, but it is offered with charity, and not to contradict Church teachings, so I think it falls under the wiggle room given by St. Augustine:) -
Heaven and Hell, as the previous poster noted, is not a physical, geographic, place.
Heaven is being in the presence of God, and Hell is being separated from God.
However, with that said, back to the question, “Heaven and Eternity - is it outside of creation?”
First, let’s look at Heaven. Yes, Heaven is very much is part of creation (Genesis 1:1). And, mankind was created to live eternally. The fall of man (Genesis Chapter 3) changed all that. At the moment of the fall, mankind (resulting of his unwise application of God’s gift of free-will), not God, created Hell.
Now, for Eternity. Eternity is outside creation, in that, Eternity has no beginning and no end. Eternity is not linear. No starting point, no ending point. So, eternity is every present (a concept known as the “Eternal Now”). This is why the Sacrifice of the Holy Mass is a representation (that is RE-presentation) of the death and resurrection of the Lord (and not merely a representation, which would mean it is purely symbolic and therefore does not support the Real Presence of Christ in the Eucharist).
Time, not eternity, was created. God gave us time as a frame of reference for man. God functions outside the constraints of time.
Hope this helps.