Thanks again for all your help !!
So in terms of an update - bride decided all layers should be chocolate Madeira. I went for 10, 8 and 6 - purely for practical reasons. I baked 2 deep cakes for each layer and plan splitting each so each tier has 3 layers. I really didn’t realise how much cake this needs !! Each cake is in the freezer. So. Much. Cake
I'm glad it all fit in the freeze box -- hope everything goes great!