I don't see these mass returns to Poland
Nor me.
Some people who were early post-2004 migrants and were middle aged (with adult kids in PL) at the time return in retirement, though some don't. Other individuals return if things haven't worked out or after a divorce or if they're genuinely unhappy there or if there's a sweetheart waiting at home or a particularly good job or inheritance to return to, however most certainly stay, especially if they've got school or university age kids.
Those people will probably always stay since their kids generally become British quite quickly and will stay there and their grandkids have little do with and little interest in the place their grandparents came from. Many migrants dream of one day returning however it doesn't usually turn out that way.
Anyway, Luton Airport is much nearer to Warsaw than Szczecin is, and a Wizzair ticket sometimes not much more than (and sometimes less than) a train from Warsaw to Wroclaw. If people want food from the old country they can get it there and Polish TV is available in the U.K. on satellite or online. Plus the standard of living is usually good and wages are higher.