In reply to JJL:
Agreed about the thermal store. You could hook it up to solar, air or ground source heat pump, electricity (as in immersion), an oil fired boiler, and a wood burner, all at the same time and it'll use whatever is the cheapest source of heat at any second.
Add in you'll get mains pressure hot water as well, and - if money is no object - then you'll be not paying a penny to anyone for life.
In terms of cost, we specced out a mahoosive thermal store + solar + a small boiler + a wood burner, all interconnected, centrally controlled, and it was about £25k (including all appliances, control mechanisms and fitting). This was a bit expensive for us at the time and we ran away. Your mileage may, naturally, vary.
Post edited at 17:15