OP
davesparks
If you are buying a contactor, you will get a wiring diagram with it. However there are two things, switched supply to the coil and when the coil activates the terminals closed by the coil are for the lights. We have a similar setup supplying seventeen lights. I did not put a key switch in as you can just switch of the timed supply with a spur supplying it all. And that gear is locked in a cupboard so no one can interfere without a tool or key. There is a seasonal time clock set for 52 degrees north so no need for a photocell in this case. Maybe the keyswitch is a bit overkill unless the public can get at it, but if they can then they can mess with the time switch.
You are aware the keyswitch is for em testing arent you, I hardly think you can call that overkill when it is a requirement of the British standard