So I was playing fallout 2 and accepted Mrs. Bishops invitation for a drink and more, and now im stuck on the roof without any earlier saves and I am to low to fight my way out. Anyone know a way out?

I usually have no problem by walking behind Mr Bishop (not in front).

You can also try sneaking.

right as I walk in the room he becomes hostile

Does he engage you in conversation? I think you can press 0 and not trigger the Hostility.

Try walking in with Sneak enabled.

Sneaking always worked for me as well. Make sure you keep as much distance between Bishop and you as possible as you sneak to the stairs. If you really can't get it done with sneaking then running is your only option. Hope you have enough AP's, otherwise you can use Jet (with the risk of addiction) to increase your AP's.

Oh, and try using multiple saves, something can always screw up and make you end up having to play through half the game again because of a crash or something.