I see your point now. To get to the base level though, is a very cheap process. You barely need more than loft insulation which is about £200 all in.Well if you want to sell a house, which is the only accurate way to determine its value, there is a legal requirement to provide an Energy Performance Certificate which assesses such things as insulation and double-glazing in awarding an A to G rating. This rating impacts on the price of the house, and often on the buyers ability to get a mortgage. So I would argue that it definitely increases property value to insulate.
You're dead right about the solar grants though. I'm looking into solar and heat pumps, and in fact I have a meeting about that at lunchtime, but a grant to help with installation would have made it a no-brainer.
The stuff I'm talking about is more proper wall and under floor insulation. The under floor insulation is hardly ever done, and could be a big deal.
Replacing gas boilers with a heat pump and coupled with a small solar PV system could be a brilliant solution for the future.