The base of any fruit cake recipe is the fruit mix. The cake batter is essentially just there to hold all of the dried fruit together. Although I have provided the recipe I used, as long as you end up with roughly the same total weight at the end you can alter the proportions to your taste. In this recipe I was short on mixed peel and currants, but bulked up with dried apricots scrounged from my baking cupboard. It's a very flexible type of cake.
Once you have your smooth surface you can take care of any flaws that are left. Marks and cracks in the icing can be hidden by taking a small ball of icing, dipping it in some cornflour or icing sugar, and rubbing it over the problem area. The icing sugar will fill the crack and blend it into the surface, smoothing it out. Other marks such as cake smears or food colouring can often be removed by brushing on a little clear alcohol, such as vodka, and then rubbing lightly with some kitchen towel. Once the liqour has dried smooth out the surface again.