In the 17th century, two cakes were made, one for the bride and one for the groom. The groom's cake would die out and the bride's cake become the main cake for the event. When the two cakes were served together, the groom's cake was typically the darker colored, rich fruit cake and generally much smaller than the bride's cake. The bride's cake was usually a simple pound cake with white icing because white was a sign of virginity and purity.
Not every bride or groom wants a homemade wedding cake, so don't pressure them to agree to let you bake. If she wants a cake from a specific bakery she loves or he thinks pies would be a fun alternative, then graciously offer to help with another part of the wedding. Depending on where you're baking and decorating, a homemade wedding cake in the middle of wedding week preparations can add a lot of stress and mess. So don't be insulted if the bride and groom aren't into the idea. Everyone needs to be on board and on the same page.
Covering a cake in marzipan uses exactly the same method as covering it in fondant. Stick the cake to the cake board with a small ball of marzipan. Now, take roughly enough marzipan to cover your cake. This can be hard to judge and is a matter of practise, so if in doubt always use more. Knead the marzipan a little, until it is smooth and pliable. Roll it out into a rough circular shape, about half a centimetre thick.
Once cooked, leave the cake to cool in the tin. When cool, remove from the tin and place on some baking parchment. Drizzle a couple of tablespoons of brandy (or your other chosen liquor) over the cake and wrap it up tightly in parchment and clingfilm or foil. Every few days unwrap the cake to feed it with another spoonful of liquor, then wrap it back up and return to a safe, temperate storage space.