There's no such thing as a Christian Law as far as I'm aware.
There is English Law and there's Turkish Law.
However for followers of Islam the Qur'an says:
Marry woman of your choice in twos' threes' or fours' but if ye fear that ye shall not be able to deal justly, (with them), then only one' [Al-Qur'an 4:3]
There are currently followers of Islam living in the UK who have multiple wives.