Consumers with first generation smart meters... if you switch supplier and the new supplier cannot operate the meter in smart mode, they will need to operate it as a traditional meter with meter readings taken manually. Energy suppliers must inform you of this risk.
Suppliers are expected to start installing second generation smart meters in the first half of 2018. All suppliers will be able to operate second generation meters. This is because the government has appointed a company - the Data and Communications Company (DCC) - to establish a new national infrastructure that will enable communications between smart meters and all energy suppliers.
First generation smart meters are expected to be connected to the new national infrastructure in the first half 2019. This will give everyone the flexibility to switch between suppliers without losing smart features.
https://www.ofgem.gov.uk/consumers/household-gas-and-electricity-guide/understand-smart-prepayment-and-other-energy-meters/smart-meters-your-rights