Edit: I misunderstood, i dont need analogue or PWM, you are right. I just need an output turned on and the TRIAC holds it until the next ZC point. Therefore one arudino board should be able to do all the circuits I could ever need for one house!
I know you don't need the relay, but I wanted a way to physically isolate both the live and neutral from the circuit. So both is over kill, but can guarantee electrical isolation.
I dont want an off the shelf system, I use a zigbee automation system already, and would like to go for a wired approach