In The UK of course despite the country being small, most of the population masses are around major Cities and towns
No shit. It's almost as if a city or a town is a place where lots of people live.
There is a kernel of a point that some areas of the country are more crowded than others. For example the south east is overcrowded (though Kent, where I live, is wierdly empty) whereas other areas of the country are in population decline. I think, particularly, the Labour govt. of the 90s and 00s could've done more to ensure that immigration was better managed (both in terms of distribution and government spending). But this isn't an argument against immigration as such.
Currently in Oldham Greater Manchester we have a situation where Romanians and Eastern blockers have pitched battles with the predominant Pakistanis.
Clearly you'd love this to be happening but it is a gross exaggeration of reality. My other half's family are in Radcliffe and Bolton and they wouldn't recognise this. There are tensions between communities in north Manchester but these are part of life and if 'pitched battles' were occurring that would be a regular feature on the news.
It is a curious thing but whenever i interface with the hospitality industry, its almost a given now that i will be talking with an Eastern block person. If i go to the lake district, most of the staff in hotels are Eastern block. How did that happen? Those jobs were once done by locals.
Here are some employment statistics going back to the 70's www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/timeseries/lf24/lms (it's not my favourite stat because it's susceptible to governmental doctoring, but that's been the case as long as it has existed). There is no compelling evidence of foreigners coming in and putting locals on the scrap heap.
The reality is that people come in from elsewhere in the world, take jobs, earn money and spend it. Every Polish cleaner or Latvian barman will spend money on food, transport, leisure etc etc. That in turn creates employment for others. They don't steal jobs, they help grow the economy (and, at the moment, help plug the massive hole in the state pension system).
This really is just common sense, you know? Again, you don't need to say anything sophisticated at all to punch holes in the immigrant haters' stock arguments.