France has an almost universal provision of state apartment blocks for young people - my son lives in one now. They are like university halls of residence, but instead of just students at one uni, they are open to anybody under 25 that has a 'personal project' - any education or training course, starting work, setting up a business, etc. Generally, people can stay up to 2 years, and most have a social worker attached to help young people into independent life - everything from tax forms to counselling.
It's brilliant - but then over half of the French economy is in the public sector - which is what the UK should be aiming for.