We are going to need to reform the rules on freehold, specifically so that potential vertical dwellings can be maximised - this will need to be Tennant centered so you don't get anonymous corporations failing in maintainng medium rise and higher rise buildings.
These will need to be built on brown field and re developed town centres, the costs will be huge as you'll need to work in an urban footprint and reconfigure around existing utilities and buildings, possibly in heritage areas too.
Well also need to repurpose office buildings to a high standard residential, and not the poorly insulated, porrly ventilated, poorly soundproofed sweat boxes they are now.
It's not easy, it's not cheap - it is a choice.