I used one of these
in last house to replace earlier one, it is not as easy as first to alter temperature but worked well with 6 options for temperature changes per day, and at around £35 did not break the bank, batteries last around 2 years, I changed every year to be on the safe side, contacts as com, N/O, N/C and you can select which with dip switch so either off if batteries fail or on if batteries fail.
I fitted this
to mothers house, it was useless, it would loose the RF link and there is not fail safe, so would over heat room. With any RF model you need to pay a little more so it fails safe.
This house fitted this
expensive but wanted mains powered, and wired com, and it can use a wired connection between thermostat and heat link, and very easy to use, the wires between the thermostat and boiler took an unknown route and using this they are only 12 volt so selected because of safety so wires only carry 12 volt.
In the main all the thermostats do is stop boilers cycling, me rooms are controlled with either one of these
or one of these
there are some little used rooms with these
so to control boiler in may house the schedules need to match between wall thermostat and radiator mounted, it does work, however likely would work better if linked so the Hive is around cheapest linked and Drayton Wiser around the best.