UK Wiring a new smart thermostat

[TheJay]

Good plan, I have in the past been called by a builder who used a Newley qualified spark to fit a nest stat to a new boiler In a new build.
bottom line was he mixed up the 230v and 24v control wires and blew the main board in the boiler.

mistakes can be made and they can be expensive.

I suspect now I need to find a new electrician who works in or near Worcester.

Can anyone recommend?