This can be true, if you have the right house. But be careful of what you wish for.
There is a government grant available to support the installation of heat pumps. Depending upon the size of the job - usually has to be about an average 3-bed house - and a sufficiently straightforward installation, then it can work out that the grant is sufficient to cover the cost of the heat pump and its installation.
It will be an air source heat pump, so a backwards aircon unit. Ground source heat pumps are a lot more expensive and the grant does not cover the full cost of those.
But there are two important issues as to whether this "free heat pump" is worth it:
Will you be sufficiently warm if you have an air source heat pump?
What will it cost to run?
Air source heat pumps deliver lower grade heat than your gas boiler, so the water in your rads will not be as hot. Unless your house is very well insulated, or your rads are seriously oversized for the current job, you might not be warm enough during the coldest part of the year. Unless your house is already arranged to the very high standards of insulation of recently built new houses, it might be very expensive to upgrade the insulation sufficiently, and/or increase size of the rads, such that the air source heat pump does the job. New houses with a heat pump would typically choose underfloor heating, or fanned air heating such as more commonly found in commercial premises, rather than conventional rads, so that the lower grade heat can do its job without being obtrusive with big rads. Many people choose to have a supplementary source of heat for the coldest days of the winter if they have an air source heat pump. It is mainly installed at locations off the gas grid, where they cannot access the cheap price of piped gas. It is most popular in places like SW Wales and SW Scotland where they have mild winters and no piped gas.
The heat uprate of a good air source heatpump is a factor of 3 - ie it pumps 3 times as much heat as it uses. But in recent times electricity has generally been about 5 times the cost of gas per kWh. Modern gas boilers run 90% efficient, so in money the ratio is about 4.5:3 rather than 5:3. But in general that means that running a heat pump costs 50% more in money to get the same amount of useful heat, on average.
Currently the prices of electricity and gas are all over the place and it remains to be seen where they will settle down. If a large increase in the price of gas becomes settled, then I would expect the elec:gas price ratio to fall from its current 5:1 to something a bit lower. But it needs to get below 3.3:1 for heat pumps to become cheaper to run than a gas boiler in the same house.