I have an analogue timer but always have heating permanently at ON and control the need for heating by altering the thermostat.
The thermostat is also a WIRED basic one (Honeywell T6360B) which I've already replaced
pressure is fine ..... circa 1.3 bar.
Have currently got heating working for only 15 minutes at a time by holding the boost button in for 10 seconds, all radiators are heated okay (this I think is a servicing function)
Hot water is fine, have reset system and bled radiators, also changed room thermostat (has illumination light when not at temperature).
Next step is heating engineer unless somebody can help :(