What you want to do is simple and doesn't require PIR sensors or CO2 sensors, it just requires a photo-detector across the entrance door and an Uno. The Uno should control a relay that controls the lighting control circuit relay.. This is done to prevent damage to the controller should there be power-line issues, a Little Safety goes a Long way. The sketch would be very easy to write however you are going to learn how to do it. There are many here that will go a long way for a polite and respectful request.
Doc