If it's not xenophobic, it's at least hypocrisy:
* the UK was one of the biggest proponents for Eastern EU expansion
* the UK did not impose any restriction on labor from the new EU members, which every EU member could do, up to 10 years from the date of the new members joining
* then, surprise-surprise!, when a lot of Poles, especially, moved to the major English speaking country in the EU, the UK decided all of a sudden they're against immigration :)
* the UK, even post-Brexit, but before Erdogan purges, through the voice of Boris Johnson, was pushing for Turkey becoming an EU members
And these ads are from 2016, when public perception of Erdogan wasn't what it was now. The angle was purely: "the Turks are going to swarm us". While the same government was pushing for Turkey in the EU.
Furthermore, the UK could just veto Turkey indefinitely. Absolutely every EU member must agree to accession of a new members.