I would not worry too much about that. I think that they will be able to handle the Fahrenheit/Celsius conversion.
:) I wasn't serious about that bit, just wondering why.
The same thing that kills a lot of cool things - regulations.
It could have something to do with power supply. Different countries have different mains voltages. I think it's a lot higher here in the Britain than in the US, which could fry a device like this perhaps.
Or perhaps not. I'm just speculating.
The control wiring for thermostats in the US is almost a common standard (RH/RC/W/Y/G) with 24 VDC. What is it in the UK?
Usually two wires, often AC mains voltage Live and Load but some newer systems use low voltage. My own house has a thermostat that wirelessly communicates with a receiver near the gas combination boiler (water heating for hot water and radiators). The receiver simply closes an electrical contact to signal heating demand.