The boiler cannot stay where it is. The bulk of the kitchen is 1950s, with the sink and units around it 60-70s. The central heating was originally run off the coal fire and back boiler but the combi was put in several years back under a grant scheme and the clowns who installed it fitted the boiler over part of a double socket!
A new fitted kitchen is a must.
The house is well insulated with full double glazing windows and doors, cavity wall insulation and generous loft insulation. The loft had been insulated, but at the time the combi was installed new thick insulation was placed over the top of the original insulation. The radiators are not microbore and are all fitted with thermostats, though manual and not programmable. Mum used to have the house like a hothouse and her monthly gas bills were never that high.
The technology for an electric combi boiler is anything but in its infancy. It appears to be a tiny self-contained immersion system for the central heating, with a flash boiler for the hot water system. I am currently waiting on a Fischer catalogue arriving but there are several other makes I am looking at.
When I had my own house we only ran the heating in the lounge, downstairs hall (the one that was on continuously), and bathroom. The only time heating was on in the bedrooms were if someone was in bed, unwell, or when my daughter used her room as her study.