Hive - which thermostats with OH?

New to OH and have done some simple home automation - having a ton of fun with this all.
I am looking to get smart about heating in my home.
I live in the UK, have a regular boiler set-up (ie gas boiler + hot water tank + expansion tank in the loft) and Hive as the controller.
I have 5 rooms which would benefit from a smart thermostat on the radiators to control their heating based on rules and triggers.

I’m reading that some people have been able to bind successfully to Hive so that’s a good first step.
But my main question is which smart thermostat is available out in the market that will let me bind with Hive (preferably direct) to open or close the flow into the radiators and as affordable as possible?
I’m not too concerned if it is a smart valve with out temp readings, as I could link room temperature sensors aside if needed. Thanks