Play the Gazala level and start at the main base when you begin. Get into a fast vehicle (plane or jeep recommended) to get there before of any bots. Go to square 1-B, or just go to the edge of the base facing the nearest area boundary then follow the boundary all the way to the left until you get there. On the map, there should also be a small gray dot signifying an AA Gun at the secret airport to point you in the correct direction. Once you get there, you should immediately see two British planes and two buildings, one with the repair, and one with health for you. There should also be an ammo supply.