We hear the term heating and ventilating engineer, to my mind, engineer means over level 3 educated, i.e. a degree. And there is a big difference between something working safely, and some thing working no only safely but efficiently.
What most want is as little heat as possible going outside, and inside rooms are only heated when required.
So step one is allow as little heat as possible to go out of the flue.
So page 4 of the installation manual and we see the output varies depending on model for example 9.1 kW to 24.3 kW and we know there is no option for a modulating thermostat, so it is controlled by the return water temperature, so the most important control device is the thermostatic radiator valve (TRV).
So how it works in general terms, each valve slowly opens or closes to regulate room temperature, as the valves close, the by-pass valve opens, as the by-pass valve opens hot water is returned to the boiler, as the hot water reaches the boiler the boiler turns down, until it hits 9.1 kW when it can't turn down any more, so it turns off, but since already turned down there is not that much heat left in the boiler so not too much energy is wasted out of the flue. However if a thermostat turns off the boiler it could still be at 24.3 kW output so more energy is wasted out of the flue.
Most boilers have some form of anti cycle software, this is normally a timer, so once the boiler turns off due to hot water returning it waits a set time, then switches back on, if hot water is still returned it increases the time it waits, if not it decreases the time it waits, so it does not fire up too often, however it can never turn off, so we fit a wall thermostat in a cool room, on ground floor, with no outside doors and no alternative heating to turn off the boiler on warm days to stop the cycling.
However we also don't want to heat the house or rooms when not occupied, so we look at timers, occupancy detectors, and geofencing.
Timers is easy, we can buy TRV heads at around £10 each which allows us to set up a schedule, so my bedroom is set to 20°C at 10 pm then 18°C at midnight then 20°C at 7 am and 17°C at 8 am. So warm to go to bed and get up, cooler through night and basic off during the day, not quite that simple as unless boiler running it does nothing, but I am sure you get the idea, now in the living room I have a more expensive TRV head, I could although I don't, set up the head with IFTTT (if this then that) to detect when my mobile phone leaves the house and then turn down heating. However I also have a Nest thermostat, which not only looks at where my wife and mine phones are, but also has occupancy detection, so if daughter is in the house when we leave, it does not turn off heating while it has detected she is in the house.
So my wall thermostat does the geofencing so the occupancy detection can override it. so we have two motorised valves, and pumps which select main house heating or granny flat heating, granny flat always turned off, used for storage only. There are 5 standard TRV heads, 4 in granny flat and one in loo, and 9 programmable TRV heads, 5 simple timed and 4 which could be linked to Nest if Nest had not withdrawn support, and can be set with phone anywhere in the world and can use IFTTT, to be frank I bought the expensive ones first, and knowing what I do now, would have used all cheap eQ-3 type.
However I unlike you don't have a gas modulating boiler, I have an old oil boiler, so turning boiler on/off for me is not really as bad as when you turn boiler on/off.
So if you really want, leaving the original thermostat in place, you could set up the house with programmable TRV heads to do all the geofencing you want, as to opening app on phone and manually setting, in the summer I will look at room temperature before setting off home, and if high, switch on the AC with the phone to start cooling down room. But in winter never look, I let the geofencing do it all. And being frank I have never altered the room temperature while away from the house, so all this expensive Nest is simply just an on/off switch, OK with more expensive boiler (over £2000 for oil) I could have a modulation control and turn boiler up and down with Nest, but unlike gas, oil does not turn up/down much, so not really worth bothering with.
So you can bring in the heating and ventilating engineer and he can set up the home to do exactly the right thing at the right time, and if your heating bill is £400 a year, he may reduce that to £300 if your very lucky, and spend £1000 doing it, so with interest it will take 25 years to pay for its self, and long before then, it will need all doing again. Or you spend £100 on 10 eQ-3 TRV heads and set just simple times in each room, and only save £50 a year, but in two years time they have paid for them selves. No wiring just replace existing TRV heads simple screw on.
I am a fine one to talk, I have installed Nest, however main reason was boiler in the granny flat, and only two wires between granny flat and where thermostat is in the house, and with Nest I can control DHW and CH from the house to flat plus keep the thermostat powered with just two wires. I was not bought to use geofencing although now we have it we use it.
So will these
do what you want? Google eQ-3 and loads of hits. Mine set eco 17°C and comfort 21°C and by pressing button with moon and * I can switch between the two. It even turns off central heating to kitchen for ½ hour when back door open while we unload food from car automatic if set to do that.
