HT heat pump, Oil system or night storage options

[Milliamp99]

I live in a 15 c timber and thatched house with night storage heaters and all electric , off gas grid and use annually 28,000 kWh and in the winter around 90-130 kWh a day, summer around 12-18 kWh, mostly HWS as the heater are switched off. We will be upgrading were possible the insulation, but this may be limited to loft and secondary glazing as its grade II listed...do we go for a HT Heat pump system and new radiator install would we really save 2 thirds due to the COP or will we never heat the house up ..would we qualify for the RHI ! had several quotes some said it would always be cold..it gets to about 18deg c anyway in the winter (-2) so anything would be an improvement , two inglenook fires and a wood burner (12kW) to assist when it gets really cold and it can do..:-)

location Suffolk (stowmarket area) property two story, approx 65 m2 1st floor and 80m2 ground floor approx 22 kW based on an online calc and u values around 1.6 for the walls etc obviously that's with everything on and -3 outside

would a Daikin HT Altherma-HT system work or are ether better options....