Hi,
I would highly recommend an automatic door. I have used a variety of doors, however have found the chucksaway the best. It is quite expensive to buy to begin with but it is well worth it. Mine only took a week or so to work it out (they are ex batts so haven't ever been outside to understand going in at dusk.) I have used both the timer and light sensor, I prefer the timer, I just make sure that it will be dark when it closes. It's harder in the summer months to do this though. I have even started using one for my turkeys. We have a lot of foxes here and have lost a lot of hens and a few cockerels to foxes.
It is definitely the best purchase I made.
Emily