It's very simple really.
full Job Guarantee - create enough jobs and pay a living wage. Take people as they are and let them show they can produce something of value to society - working for the public good.
Of course with open borders that would mean you would likely end up with an awful lot of unemployed on your doorstep from the entire open borders area and, much as we'd like to help everybody, the country and the infrastructure can't cope with that.
Firstly there is the ecological footprint of the population on the country to consider, and then the impact on the social infrastructure - which takes time to augment even if you invest properly.
So as part of implementing the Job Guarantee you restrict the open borders to other parts of the world that have an equivalent Job Guarantee programme and social infrastructure. If you don't come from such country then you have to apply for a visa and be assessed.
It's quite difficult for a foreign leader to argue against that position, because if they do then they are essentially saying they want to dump their unemployment in the UK rather than deal with it themselves. The push back would be: Implement a Job Guarantee and we'll gladly remove the restrictions for your country.
So as well as solving the unemployment and poverty problem permanently, you make the Job Guarantee a viral requirement for open access to your advanced economy. At a stroke we have a positive reason for a temporary restriction on free movement.
The Job Guarantee could very easily become the GPL for the people - guaranteeing you a job and an income wherever you go.