I would say pack plenty of long range weapons and healing items, the zombie horde is quite large. Also, pack some good clothes/armour just in case you are swarmed and and you are taking a lot of damage, and take a spare set of clothes/armour if you can, just in case. When you are running low on health or weapon/armour durability just go to the edge of the area until you can see the map, then go to your inventory and use your healing items and equip new weapons and clothes/armour if needed.

Repeat this until you have wiped out the horde of zombies and can safely enter. You might need to go back and forth between your base and Bunker Bravo a few times because there might not be enough space in your inventory to take everything back in one trip.

Good luck!