let's take this magical million refugee number and take it for a spin. first of all, it's not a million refugee among 63 million population, which still'd be significant, because they will try/want to go in the place that gives them the best chances for a job and stability. And since they don't really know the state they're entering, they will try to stick into the major and best known cities.
London (pop: 8mil) will end up with the majority, so now you're looking to quite the cultural shift, even assuming housing is widely available, which introduces the second problem: they will try and stick together. Look around at your city: chances are you have the Chinese quarter, the Italian quarter etc. That's because people in an alien culture will try and stick together, as simple as that, but the effect is twofold: once an area becomes specific, it will start to be unwelcoming to other cultures and a real problem to police. Especially if you don't get those million people a job or other means for living.
At least the first generation will known they have it better, even if they barely manage to live by it's better than being shelled. But in twenty years, you'll get to deal with the second generation, which will grow with the local culture and with wants aligned with the state they're living in. Youth unemployment is a problem, no matter what, even not accounting the second generation will grow with the local culture but face parent level of discrimination. But will they feel unemployment is due the current crisis, or will they feel discriminated against?
Second generation radicalizing is a real problem. Scratch the surface before sensationalist press touting 'the terrorist was Belgian/French/USA' to discard the immigrants problem, and you'll find often a second generation immigrant.
Now the problem is not immigration, you see, the problem is that logistic, housing and integration issues aren't being addressed and haven't been addressed for years, and this is how you end up with gullible population ready to vote for the first nationalistic party claiming to have a solution (even if closing frontiers wouldn't solve the problem in Europe and wouldn't address the problem, only limit and curtail it)
But you try and address those problems, and you get immediately labeled racist ¯\_(ツ)_/¯