The question of disconnection by means of a smart meter is somewhat moot.
The disconnection of Domestic electricity supply is governed by "Standard Conditions of Electricity Supply Licence" which is a document issued under the Electricity Act 1989. Buried among its 569 pages, is this:
27.09 The licensee must not Disconnect a Domestic Premises at which the Domestic Customer has not paid Charges unless it has first taken all reasonable steps to recover those charges…
27.10 The licensee must not Disconnect, in Winter, a Domestic Premises at which the Domestic Customer has not paid Charges if it knows or has reason to believe that the customer is of Pensionable Age and lives alone or lives only with persons who are of Pensionable Age or under the age of 18.
27.11 The licensee must take all reasonable steps to avoid Disconnecting, in Winter, a Domestic Premises at which the Domestic Customer has not paid Charges if the occupants of the premises include a person who is of Pensionable Age, disabled
or chronically sick and to whom paragraph 27.10 does not apply.
There is also provision in the legislation to prevent disconnection (to any domestic supply) unless seven days notice, in writing, has been provided.
I've not looked at the equivalent legislation for Gas supply - if it too runs to 500 plus pages somebody else can do it but I imagine similar protections are in place.
But the important point is this: these protections exist regardless of the type of meter the customer has. The energy supplier must abide by these protections whether he has a conventional meter or a smart meter. They may be able to disconnect remotely via a smart meter, but they are not entitled to do so unless the legislation is followed.
I am increasingly of the belief that the OP of this question is once again frantically searching for circumstances to highlight the way