Open it yourself.

You are already feeling all protective of Milly so tell her to stay in the car, which she readily agrees to. You cautiously approach the gate trying to stay as near to the car as you can and as far from the hedges as possible. You glance back to Milly sitting anxiously in the car and give her a reassuring smile before you turn to the gate again.
Its fairly easy to untie the plastic twine securing the gate. Lucky it's not padlocked you think to yourself briefly as you pull the catch and pull the gate to open it. As it begins to move it starts to screech.
Suddenly everything is a bit of a blur as there's sudden movement from the hedge on all sides. Zombies burst from sides as you stand still for a moment in shock and panic. Your reactions do kick in as you run for the open car door. However, it's on the far side and a zombie grabs you. You throw your weight forward and rip free of the zombies grasps but hit into the open car door closing it. As you fall on your face you hear Milly scream as zombies begin to scratch at the car and swarm over you. As you begin to struggle with the first one on you and then the second before you're completely swamped you hear the car engine rev and before consciousness goes from the ripping and biting you could of sworn the car began to move forward.

[Depending on feedback I may use this as a POV change to Milly, so please tell me if you'd be interested in this.]