The HR92's are not the valves themselves, just a motorised actuator that presses on to the pin within the valve body.
The HR92's come with a plastic adapter to enable them to fit onto valves that were originally a Danfoss RA fitting, or will fit directly onto the 30x1.5mm thread of TRV's that already have the metal 30x1.5mm thread.
I found the cheapest Screwfix TRV set happened to have the 30x1.5mm metal valve type by pure luck & coincidence. I think you can buy just the TRV valve body from plumbing suppliers but the SF kit even included the lockshield valves for less than £10
Hope this is helpful ?