I agree Dora -- is there really a huge tolerance for intolerance? Do you have loads of Brits saying, sure, let's go ahead and have that sharia law put in place? Is everyone saying, sure go ahead with your FGM and honour killings? I don't think so.
But as you say, what do you DO about it? I actually agree that a lot more could be done, for example FGM should be illegal and anyone caught practicing repeatedly should be deported if not a citizen. But that doesn't mean becoming intolerant of whole communities. We should focus on the acts that people commit, not the people themselves.
It's actually an interesting point whether the UK should have a US-style bill of rights. I'm originally from the States and I think this would be a good idea. The First Amendment is a huge part of American culture, very deeply believed in, and offers important legal protections not just for the majority culture but for minorities too. This would be important because you need that reciprocity for social peace if it's just about the majority imposing its will on minorities, you will always have tensions (rightly or wrongly).
The American style is helpful because if you tell people they shouldn't do something because it's against British values, there is a whole contested discussion about what is British and how values change over time. Whereas in the US you can just say, that's unconstitutional. But at the same time, people will know that if someone tries to do something intolerant to them, it will also be unconstitutional. You can't have sharia law but at the same time you can't have fundamentalist Christians coming into your schools and forcing your children to go to mass or whatever.