I will first as a question:- Do you have thermostatic radiator valves?
The reason is there are now thermostats with built in timers so you can have different temperatures at different times of day rather than simply on/off. This also means no need for frost stat as it does that job as well.
I use one of
these 
however if you already have thermostatic radiator valves it may be rather pointless.
I have thermostatic radiator valves upstairs but not down stairs and very pleased with the control the thermostat with timer gives me.
With thermostatic radiator valves then really the thermostat is only there to stop the central heating firing up in the summer. Putting the thermostat in the morning sun would make sense as it would stop the central heating coming on when we have a warm day.
The boiler will also change what you need with thermostatic radiator valves as some have anti-cycle built in and others don't. The new clever boilers have a sort of memory and monitor how long it takes for hot water to return.
So much has changed so what may be correct for one system is completely wrong for another. Years ago you always had one radiator without a thermostatic radiator valve. However that would mess up the anti-cycle system on a more modern system and a by-pass valve is used instead.
Even with the older systems there were huge variations. With thermo syphon often there was no control over domestic hot water temperature and you were forced to time when the boiler fired up for domestic hot water. With others there was a thermostat on the tank and a motorised valve.
The timers needed configuring for type used often with a mechanical selector as with thermo syphon you can't turn off hot water and just have central heating.
You clearly do have motorised valves but there are two and three position which look the same. One gives just either / or and the other either / or / both.
With some systems you send a signal to boiler and once turned off it continues to run until cool. Others simply turn the boiler on and off.
So sorry you will need to work out what you have first before you can get any good advise.
One of the problems even us electricians and it would seem more so with plumbers get caught out because of changes we are unaware of. A large firm specialising in one day blitz central heating system changes did my parents house and left it with an illegal system. That was 2 so called engineers surveyed it. And 1 electrician and 4 plumbers fitted it. Finally an inspector viewed it and still ended up with an illegal system with a power shower pump sucking from the mains supply.
As a result I don't trust plumbers.
