Are there such a thing as ZWAVE radiator valves in particular with the M30 x 1.5 fitting which is the standard for UK radiators. Also Would you need a separate hub or can OH handle it by itself, i.e turning the valve on and off and setting the temp
Sure - plenty of options exist.
You will need a zwave interface - ie a dongle - to communicate with zwave devices, but you don’t need a “hub” as such. The dongle is reasonably low cost (<50 quid) compared to hubs (>>100 quid - but likely a LOT more than this).