No, it isn’t. Please stop believing the hype/doom merchants, come to the UK and see firsthand rather than what FR or US media tells you. 96% of the UK is NOT Muslim, 92% is white European. Three parts of the uk have tiny muslim/ethnic pops. Muslims are NOT the largest UK ethnic group by far, contrary to myth. And for all the noise of scum like Choudray (who is in fact a dangerous but isolated figure), UK Muslims have little or no major political, social or economic power.
Does the UK have a problem with young, extreme Islamists?. Yes, but the idea the UK is some dhimmi state just away from a Caliphate is nonsense.
Yes, it will. I travel across Europe every year, and as much as I oppose the recent refugee intake, the idea that the great cities are off limits now is nonsense. They are still great cities and perfectly safe and fine to visit.
I lived in the UK a few decades ago. The last time I visited London, I was shocked to find the elevated number of Muslims. I was also shocked to find that many, if not most, shop signs were in English and Arabic. In the Southwestern USA, many of our shop signs are in English and Spanish. In London, we stayed at an upscale hotel near Hyde Park. The room service menu had an extra Halal section. Maybe you don’t see the transition because you live there. But it is certainly very different from the England of the 80’s.