It's pretty obvious. You need to become a housing developer and build your own homes. These would be a mixture of affordable (even though the current definition is still not really affordable for most people) and rental properties. This would cut out the property developers and allow the council to make a profit margin on the sold homes and a guaranteed income, essentially forever, on the rental properties.
Yes it requires certain skillsets to achieve this in a successful manner but they are available in the market.
Any other option is just going to be window dressing and fail as developers are experts at finding ways around the rules.