Your heating system should be left on constant and the room stat turned down to 10 degrease. That way if we have a freak cold patch the house will never get to cold. All radiator valves should be left open. This is because if a TRV (Thermostatic Radiator Valve) is left shut for six months the packing inside the valve might get stuck and when the system is turned back on the radiator will not work.
If you have an old boiler (not condensing) it is important to let the boiler circulate at least once a week. This is to let the pump run and make sure it does not seize up. Feel free to get in touch should you require boiler repairs or servicing.