What about a couple of HR90's for your hallway and utility room ?
https://www.honeywelluk.com/products...nic-TRVs/HR90/
They look similar to the HR92 but they are completely standalone. They won't communicate with Evohome, but you can program a schedule into them. So you could program them to be off at night to ensure those two rooms don't heat while only your bedroom is on, and on during the day at a suitable temperature - but they will only heat up if other zones are calling for heat and not if the system is off. But that may be just what you need for a hallway and utility room.