i'm in a chrisis, i can't find a sugar free fondant recipe, but i have found a sugar free cookies recipe, so i'm wondering if i can use cookie dough instead of fondant icing to cover a cake, i mean you might think it's stupid but its so crazy it just might work, anyone?

I don't know if fondant and cookie dough can be interchangeable. Fondant is formulated as no-bake, while dough is intended to be finished with an application of heat. Additionally, unbaked dough should not be consumed. So with that in mind, can you use fondant with instructions for peeling it from the cake and disposing it?

If you're willing to experiment, you can make your own sugar-free marshmallow fondant.  The experimental part is that a tried-and-true MMF recipe may not act quite the same with slightly different ingredients.  A couple of trial runs may be needed to see how it works.

I found sugar-free marshmallows and sugar-free confectioners sugar (quite a paradox!) online.  Amazon was the easiest search. I'm sure there are others available.

https://www.amazon.com/Marshmallows-Sugar-Gluten-Free-Marshmellow/dp/B00297Z00W

https://www.amazon.com/Swerve-Sweetener-Confectioners-12-oz/dp/B0079OYIFS/ref=sr_1_3_s_it?s=grocery&ie=UTF8&qid=1497112170&sr=1-3&keywords=sugar+free+confectioners+sugar

If you're really feeling adventurous, there are recipes for home-made sugar-free marshmallows, and confectioners sugar.  Many when I googled - here are two.

https://dessertswithbenefits.com/healthy-homemade-sugar-free-marshmallows/

https://www.splenda.com/recipes/powdered-sugar-recipe

As always, have fun baking. Good luck.