Once you've decided to build a bugout cabin the next step is figuring out what you wanna do with the inside. Even though this is a bug out shelter you should make an attempt to have it be homey on the inside. After all you may be here a while.
Ideally the basement will be the main storage so shelving will be a good idea. Several rows of floor to ceiling shelves toward the back will be good. This way you can easily organize your essentials, food, water, ammo, extra blankets, etc. You will want a stack of wood down here too if you plan on having a wood burning stove. This way you will always have a pile of dry wood to burn.
The Main floor
The main floor is where you will be spending most of your time so be sure to furnish it with a pub table for the kitchen, a nice comfortable couch, books, board games, good smelling candles for comfort, a wood stove, and any other things necessary to make you comfortable for the long haul. If you can build the cabin yourself you have the skill to build the furniture for your house too. Search rustic mission style furniture and you will see most of it is simple to build and made from pine lumber.
The loft will be the bedroom so this area will have your bed, dresser, armoire, nightstands, etc. Make sure you have nice warm blankets. A wood burning fireplace will boost morale, be romantic, and provide efficient warmth. Curtains are a good idea even though the cabin is in the middle of no where. Curtains are nice because they provide privacy and will possibly deture the hordes of zombies because they wont see you.
However you decide to design your cabin is up to you but remember to make it liveable you might be there awhile. Also plan for the reality that there may not be a power grid anymore so have backups or alternitives to all your electic stuff.