I'm confused, are you accusing the idea that multiculturalism doesn't work as being racist? There is ample evidence that it in fact doesn't work: that an underclass is inevitable and that status applied to an entire culture is immensely damaging.
The idea that there is a "poor, uneducated, unacculturate" immigrant underclass in the UK is a racist lie. Recently arrived immigrants often find themselves at a disadvantage, but 2nd & 3rd generation communities are often wealthier, and better educated than "natives".
Five or ten years ago, I would have told you that this kind of politicised bigotry was entirely outside the British mainstream... only practised by a tiny, shabby fringe. These days, I'm dismayed to admit that the BNP and their UKIP mini-me's have managed to spread their filthy ideas much more widely.
I'm not really familiar with the situation in the UK. My very vague understanding is that the native Britons are so bad, with their chavs and yobs and twelve-year-old moms, that no group of immigrants, no matter how poor or uneducated, could make things worse. [1]
However, it seems to me that you feel so strongly about the issue that, even if immigration did create big social problems that wouldn't otherwise exist, you still would be accusing anyone who pointed that out of being racist. Basically, "that's racist" is not the conclusion of your argument, but rather the premise, and you're using it as a thought-terminating cliché.
Or at least that's my impression as an uninvolved observer, even though I'm more sympathetic to your position.
[1: I hope the British hackers don't get too offended, that was largely tongue-in-cheek.]
Obviously you are right, the situation is more nuanced. However, it's futile to debate those nuances with someone who is simply looking for sound-bites to push a hateful agenda. Example:
1. I did not expect my comment to get that much attention.
2. My LOL is sarcastic - I am sad that tolerance approached such a level that it hurts the country.
3. That phrase is what the current country leader said:
http://www.bbc.co.uk/news/uk-politics-12371994
When issues are not addressed on time they produce nazi states.
On the flip side, loudmouth, self-appointed, "spokesmen" of the Asian Muslim community such as Mehdi Hasan or Anjem Choudhry really don't help matters very much.
Politicised Islam in Britain - and the associated terrorist actions that result - has done a great deal to generate support for parties and groups such as BNP, UKIP, or EDL.