i am making my cake - but cheating hugely!!!!
i am making a fruit cake for the bottom tier - serves about 100, then my other tiers are made from polystyrene blocks so that 1) they are all neat and perfect hight and 2) i can ice them in plenty of time for the wedding so have time to re-do if they go wrong!
I am then makeing a chocolate orange mud cake and a sponge cake covered in white icing to have as cutting cakes out the back - then it doesn't matter if the icing goes wrong cos no-one can see it and it will be cut up by the time it comes out - and no-one will know that the actual cake was fake as we'll still be able to cut the bottom tier!!
if you know someone who can decently cover a cake, this could be an option....(if that all makes sense!)