Generally 18/19% is bandied about in terms of the official stats on the population not born here, and of that about a quarter may be from the UK, and maybe another quarter or so from Poland
But we’ve gone beyond 5m since the last census so the 2016 headcount is already well out of date, plus of course how realistic is this, given many will not fill in census forms.
White Irish is quite widely used in stats/reports that I’ve seen, not sure we should go down the road of making our population stats overly ‘politically correct’