More like 3000/month.

Got a source for that figure?

Only 55,000 heat pumps were sold in the UK last year, compared with more than 620,000 in France. Twenty other European countries also had higher installation rates than the UK

That looks at insulation on its own. When you switch to a heat pump, it cuts the actual energy use at the home to about 1/3 of what it was when you burned gas or oil, and enables the use of non-emitting energy sources to supply the heat pump.

This means that the CO2 emissions drop, even if people decide to heat and cool their living space more.