We have reduced our elec use by about 30% over the last few years. We have done all we can (various modes of insulation, modifying our behaviour, solar thermal, solar PV, energy controls, new gas boiler).
Solar thermal was not optimally designed but works up to a point. Solar PV promising but new May 2010.
Pressurise to make sure accredited companies are good performers so we can trust them. One of our companies was accredited but a poor performer. Our second was excellent. Grill them before you leap and get more than one quote. We rely on them to advise us in new technology.