I personally do not believe in "heaven" or "hell". I believe that we get reincarnated, and keep coming back until we have learned everything we were supposed to. What happens after that? I am sure there are other realms or planes of existence - but I don't believe in the classical versions of heaven being full of angels with fluffy white wings, or hell being a fiery pit where you're punished forever!
Is your fear based on the fact that you feel you are not living in a way deserving of anything else? If so, I think that is the real fear you need to work on - just my opinions :)