relay circuit help

[bicolormoth]

I am trying to build a circuit that will change over from 230AC to a 12VDC supply in the event of a power cut. This is to run 'services' totalling around 500w to a max of 750w.
I have based my design , so far, on a set of 10A DPCO relays, a 12v - 85Amp/hr liesure battery, a 1000w /12v DC-230AC Inverter.

I need to set it up so that the relay cicuit is usually on the AC supply. in the event of a power cut the relay switches over to the DC circuit so that the services draw from the inverter/battery supply.
i also need the relay(s) to reset to the AC supply int he event that it becomes available. if the AC supply stays off then i would expect the DC supply to run for up to 30 hrs (maybe using multiple leisure batteries in parralel.)
there will also be a charger for the battery, either solar ; wind turbine, or AC mains. for when the battery is not being used.

I have tried to figure out a circuit but gave up. so i have drawn a simple diagram of the components and hope someone can help me with the circuit & correct components.

[bicolormoth]

i have had another go a the circuit. maybe this is more like what i need. ?