It’ll come off your main incomer mate, which I guess is in a box sunk in the wall (being a new build most are)
I’d probably search on whatever manufacturers website you choose for accredited electricians. It’s always luck of the draw though sadly as with most trades!
If you get stuck let me know, I know a few sparkies around the London area
Cool, will do. A lot of the companies like podpoint seem to want you to book and pay and then they’ll survey (in person). Then you can say yay or nay if additional cost/complexity arise.