Yeah I got that part, maybe you're misreading. You seem to be interested in advertising that you've read all this stuff, which is great, a lot of people have. But you aren't really addressing the problem statement, so I'll state it clearly: no one gives a shit about a 2.6% hourly wage increase
over 20 years. They don't care because immigration comes with a bunch of other externalities, that are very near term, that academics deliberately remove from their models. "Natives get a slice ... of 1.7-2.6% ... over the course of 20 years" is not a convincing argument, which is why most of the quantitative debate about immigration is largely academic. If the benefits were so obvious we wouldn't need a team of nerds to tell us that, well, actually your hourly wages do go up ... eventually. Insofar as you care about some sort of policy outcome here, you are going to have to figure out a different way to frame this.
I'm not familiar with zoning laws in the UK to comment, so, sure. Maybe a byzantine zoning bureaucracy is the problem there, that does ring distinctly "British" to me.
I haven't read the Mariel study, and honestly I don't really have any interest in it because the underlying story is that Cubans just replicated their own economic structures in a hyper-contained locality, with significant ethnic solidarity given a shared history of hardship. Again, there's qualitative aspects to this that economists - especially the econometricaly inclined - struggle with.