I respect all your views and identify with your fears.
However, please think about the fact that Christianity will only weaken in the Country if YOU as the general public allow it. Go to church more, speak out about on Christian values around every topics, support the Church of England or the Catholic Church if you really are concerned about other religions taking control. Then and only then can you rightly say you are afraid of another religions influx into this country!
As another point also consider Islamic teaching revolve around there being just one God, as with the Christian Church, and that religion recognises Jesus Christ, but as a Prophet, not as the son of God. When you actually read the Holy Qur'an you will see that the teachings correlate closely with those in the Holly Bible.
There is nothing to fear from true Islam, apart from how certain people interpret the meanings, that has transpired over time. Just consider as to how currently the Christian Church has strong elements who oppose women bishops, same sex marriage and homosexuality. Those individuals would love to impose their beliefs on all of us, which they think can be based on Bible teachings, just as you fear Islam would. But that only actually transpires if you all, the great people of this country allow it. Then also think how our pagan ancestors felt when Christianity entered the country all those centuries ago, but actually that religion still exists out there, living alongside all other religions.
I would also comment on the statement that "Islam is not a religion but a way of life". ALL religions, which Islam is most certainly, ARE a way of life, dictating the way people act, their morals, principles, their judgments, what they do and when. True Christians, as I try to be as a Child of God, follow a certain way of life, as my adopted people the Maltese do, living their lives around their religion with everything considering the Holy Mary. Everywhere you will see little shrines dedicated to her, even on the old buses, and Maltese dutifully crossing themselves in front of them (who wouldn't when going on Maltese roads!!) and a set annual calender of Church festivaties, with street parades. They live their lives around the Catholic Church, talking regularly to the priest to seek guidance on how they should live, and of course receiving confession.
In Britain we are a far more secular society, but there are still strong Church elements that rule our lives, dictate our laws, and lay down the way we should truly live within God's love. The ten commandments greatly influence our laws, and mean for instance we cannot go around killing our fellow man without due punishment. No, as for the last 500 years, the Church of England has worked alongside the monarchy and our government to administer the country, forming the way we live.
To consider that Islam is somehow detrimental to our way of life is far from the truth. They, and us, will continue to try and obey God's laws, with the teachings of Jesus Christ or Mohamed being used as a base to justify our actions. As already stated the teaching held within both the Holy Bible and the Holy Qur'an are so similar the differences are not worth considering. The only true concern would be as to how certain individuals interupt the teachings, but that, as stated previously, is true of the Christian Church as well.
In conclusion all I am concerned with is how the general public, mankind, act to either support the British Democracy or not, how they live, how they following the path of greed and evil pursuit, or not. Religions do not concern me as I do not belong to one, but try and understand all as a Child of God privately worshiping him directly and working towards implementing my life according to his laws.
To fear other religions is a severe weakness, and remember it has caused mass hysteria before in this country alone with countless innocent victims suffering as a result. Wars, public burning, hangings, and other gruesome events have marred our history. Do not let this happen again for the sake of our children, grandchildren, and those to come. God bless us. Believe in him fully and you will have no fear.