It is wrong to call Sharia "law". It is a system of opinions made by very narrowly educated individuals. The validity of their opinion only stretches to their immediate community and the same Quranic text can be interpreted with different meaning according to the necessities of the time, and the disposition of the "scholar". Britain has a system of civil law, based on precedent, accumulated and formalized, over a very long period of time. That system should be sufficient for all resident of that country.
Sharia law is outdated and cruel, and does not have a place in the modern world, let alone in Great Britian. The modern court system is a better way to settle disputes, or social practices like divorce. Sharia Law also judges Jewish people and Christians as lower class citizens, which is something that would not exactly fit in in Britian.
Sharia law is completely alien to the customs and traditions of Britain. As it is religious based, it is also discriminatory and would exclude large sections of the British population. In addition, it is a completely irrational and horribly antiquated system of 'justice'. There is no sane reason Britain would ever consider implementing such a system.
Its an archaic belief system that not only is unjust,but its extremely unjust towards females. This isn't 10 bc, you cant get away with actions like that now. If you want to move back into the dark ages, then by all means adopt a silly outdated law. I for one oppose it.
Look, Britain is already a theocracy. It's a mostly-benign theocracy, but it is still one. Just look back through history to see how brutal religious law was in Britain. If you impose Sharia now, it could wind up like it was centuries ago. Religious control makes places much less pleasant.
No, they do not need to adopt this new type of law, because the system that they have in place now is working great, and has been working great for a long time. I do not think they need to change their system unless they are having problems with it.