... can you cover a dark chocolate ganache with white fondant without it looking 'dirty' or showing through?? Or would I be safer making a white choc ganache - too sweet for me!

I've done it before and never had a problem with it showing through. Just don't roll the fondant too thin 1/8-1/4 inch is good.

Yes you can. The white wedding cake in my album was dark chocolate ganache covered with only a thin layer of fondant (about 3mm) and it didn't show through at all. I only use ganache under fondant and have never had a problem with it showing through light colours.

I used a light color fondant over the regular chocolate ganache this weekend and you couldn't tell at all.

Thanks for your help! What would I do without this website?!