It doesnt sound like a pressure issue if your hot water is working, as they use the same pressurised system.
What thermostat or heating controls\timers do you have which control the central heating?
Is that showing a call for heat?
Do you know what model of honeywell thermostat you have?
Ok there should be another box near the boiler, do you know what model that is?
The relay BDR91 which is square in shape located near the boiler should have two lights on it, next to a button, can you advise what colour light(s) are shown and if they are flashing?
Certainly, can you advise what lights are showing on the honeywell receiver?
Does the device look like the one here.
Hi Michael, I havent heard back from you, please let me know if you need any further assistance.