Is there a vegan alternative to chocolate ganache which you put underneath the fondant?

I sometimes make ganache with soy milk, but I have never played with it under fondant.

do vegans eat normal chocolate?

I think it depends on the reasons a person is vegan. Of course, you would have to read the ingredients on the chocolate you are buying. Who are you making it for? Some vegans will be picky about the sugar as well where others are only concerned about dairy products in chocolate.