Replacing existing wired controlling and programmable thermostat

I have a Worcester Greenstar 24i system boiler connected to a Honeywell ST2400C controller which is connected to a Honeywell CM907 programmable thermostat.

I do not know if the current wiring to the programmer etc is via a wiring centre as the wiring from the boiler to the controller is boxed away and access extremely difficult.

I want to upgrade to a smart thermostat and also control the hot water as well as heating.

Is this possible? If so, what would I need and how would it connect?

Thanks