Let me try and hit the nail on the head. It is not about those that have come. IT's ABOUT THOSE THAT ARE TO COME. if you can tell me how many, and of course you can't, and how we are to accommodate them, ( a city the size of Birmingham, every three of four years ) then I am intelligent enough to balance it , but neither you nor anyone else is prepared to say.
If people came to live in your mansion and told you it was OK because there was a nil cost to you when you look at what they eat and how much they contribute, you might say, well how many are coming, who are they, and eventually your mansion will not sensibly be able to accommodate any more.
Agreed we should know and have plans, but only half come from the EU...hence their are 2 issues you are talking about:
EU immigration - this has always ebbed and flowed between countries that are doing well and the others...hence in the 80's the Brits went to work in Germany...hence the poles initially came to the UK, but many are going home.
None EU immigration - aslong as we help to create wars then this will happen, but once again it ebbs and flows. Even if we did not create a war, drought, etc it is the right thing to do as humans and to help humanity. Maybe stopping the reasons why people uproot their families and lives etc to move is the thing we should focus on, rather than whinging about a problem happening with immigration, when we created the reason.