I found this at baking 911.
You can freeze a Fondant covered cake especially if you want it to keep for long term storage for up to 2 months. However, if it contains creams, custards or other perishable fillings, you can't. If the cake is frozen and it then thaws, do so in its wrappings. That's so condensation will adhere to the wrappers, not the Fondant. But, again make us of an air conditioned room to thaw it in.
However, I have heard that certain brands of Fondant may freeze and thaw better than others. I, however, not knowing whether or not the brand I used was optimal for freezing, froze the top layer of my Fondant-covered wedding cake for a year (I wouldn't do it for a cake that I was going to use for a wedding or event). However, I made sure that the cake remained covered in its wrappers (2 layers of plastic wrap) and then foil, and was placed at the cool side of room temperature to thaw. This is the best case scenario and the cake thawed nicely, but it didn't look as nice as when it was freshly made -- probably because it was a year old.