Borrowing more and more is not a good idea. Could we please see sense and cancel the benighted HS train schemes? This would save billions and billions of expenditure. Some of the savings could upgrade the lines we have. At the cancellation a lot of houses which have to be compulsorily purchased will remain as homes for the families which occupy them and there will be plenty of spare money left over to divert to accommodating others.
I said 'accommodate' because I share EDDIE'S view about the inadvisability of permanently losing green belt land. I submit an idea which may sound daft, but please think about it. I have had several very comfortable, lengthy holidays in well-appointed static caravans on sites.
There is sanitation, water, electricity and gas. They have double-glazing, central-heating, shower-rooms, 3 bedrooms, fully-equipped kitchens, dining areas and luxurious lounges with all the gadgets you could need. Many people chose to live in them. They take up less room than house, are cheaper, building them would provide a variety of employment, could be rented out by councils very reasonably and would provide at least a 20 year bulwark against the current flood of homelessness, allowing a breathing space during which building could commence on brownfield sites.
Most importantly, at the end of their lives, the land would easily revert to green sites.
As others have said, the problem is that we are full.