On Sun, 26 Feb 2017 11:17:02 -0800 (PST), Murmansk wrote:

Part of me wants to install a Hive system but as a halfway house I'm
wondering about about replacing the basic thermostat with a digital one

Unless you really need the abilty to control the heating remotely a
programmable stat will be perfectly satisactory.

"really need" in that the flat is unoccupied fairly often on an
irregular basis for unpredictable periods of time. So "holiday mode"
of a programable stat won't be usefull.

Even then if the flat up to reasonably recent insulation standards it
probably won't take long to warm up from a set back temperature
anyway.

--
Cheers
Dave.