OVO have a gateway device that works over LAN. I’ve got one, until recently you could monitor true real time usage of Electricity and Gas and use this data to automate anything on smartthings. OVO have pulled that functionality and reduced it to a Dumb reporting device, so I can see usage but only 1 day behind. This is reportedly because of complaints about accuracy though I never had any issues.
Don’t expect most UK energy companies to engage with HA users, unless there is profit in it.
here’s the page for the OVO smart app [Release] OVO Energy (Connect) V2.2.5 (Smart Meter OVO customers)