I have some evaporated milk and regular milk on hand. Can either one of these be used as a substitute for whipping cream?

It totally depends on how it's used in the recipe. We'd have to see the recipe to advise you.

It's so much easier to find substitutes for COOKING than for BAKING (and decorating).

Here's a substitution chart:
(Haven't tried any of the substitutes.)

http://www.recipegoldmine.com/kitchart/kitchart10.html

I can't say that I would substitute evaporated milk for whipping cream in a whipped cream frosting recipe.....

HTH