No not doing anything with radiator valves right now. I'm actually using an evohome system instead. So I can't help you with that. I did do a high level compare once between a system like evohome and potentially setting one up yourself. If you do it with domoticz or similar you would need the ...

Z-wave does not work via wifi. Its a mesh network protocol, and you do need "something" to talk to it. That aeon Z-wave gen 5 stick is a possibility. There's also a raspberry pi expansion card / thing you can get. They are similar in price, but the usb stick would allow you to move to a nas / pc ...