My moms birthday was last month and i made a fondant cake for the first time for her birthday. I used marshmallow fondant to cover it, tinted a minty green and added red roses and a red bead border in buttercream (hey you got to stick to what you know right :D) Inside was my moms favourite; red velvet with cream cheese.
One thing i noticed about using marshmallow fondant instead or store bought is that 1. It tastes soooooo much better and 2. It will either break very easily (not have any stretch) or retract a lot (too much stretch). But the end result is always very nice and smooth. Just be patient and don't get too frustrated:)