AVS30 is the domestic electrical circuit product choice:
Domestic ring/radial circuits normally have 30/32 MCB protecting them. The consumer fuse box should have an existing 30/32 amp MCB to protect the existing ring main circuit. A 30amp MCB will protect the AVS30 relay contacts (relay contacted rated at 30amps).
Assuming the AVS30 relay contacts are wired after MCB and before ring main, be aware that when this trips you  will lose supply to all connected on this.
The AVS100 is required if the supply exceeds 30Amps.