You basically just described things anyone can see during a weekend piss up in many cities throughout the country, irrespective of colour, nationality or race. It's bizarre, because as someone who travels a fair bit, I'd say it's us Brits who have the worst reputation globally for being unruly in our night life. I mean, places like Ibiza, Magaluf, Ayia Napa etc, we basically popularised these insane clubbing destinations where you can see pretty much all manner of depravity and craziness.
But don't you think a lot of that has much more to do with the socio economics of their situation, than it does their origin? If these places are as shitty as you say, it sounds like the local councils are under representing them, or not allocating the proper funding and resources to deal with it all. Perhaps they lack the funding, who knows, but the added tensions, hatred and violence from the bigots, racists etc probably isn't helping.
Does definitely sound like a right mess from reading the articles, but I'm sure a lot of it has been exasperated by the right wing press. Hell from your Google links there are so many. There's also a few Britain First links that popped up with a video where things are clearly exaggerated, and I'd say one Britain First fella is on camera even harassing the Roma children on the streets. Not to mention they speak of all these concocted stories of Muslims abusing them during their leafleting (which conveniently they never manage to capture on film). If this is the sort of bollocks people have coverage to, it's no wonder tension are rife. Any people feeling victimised or threatened (this goes for both sides) are going to be more likely to act up in retaliation. The calls to have these people thrown out and all the rest, is not the way forward.