Hi Kevin, presume you are notifying L.A. bldg control b4 starting! it's the law! Part P & all that!
anyway in answer to your question, don't think you can buy D-P light switches!
There is a move towards D-P switched sockets, also with twin earth terms. which were intended for computer circuits.
Problem with them is they tend to cause nuisance RCD tripping when switched as if N breaks slightly b4 L then RCD can see a fault if the socket is supplying a load when switched,