Surrey is outside London so if he will need to commute into London it does have a small pakistani population living there. Walthmstow and East Ham have a very large pakistani population. If yoour cousion is coming to london to work/ study he should also see how far his uni/ work place is from where he lives and would it be convient for him to travel there. Tube can be a killer in the morning and evening.
Here is the metropolitan police crime figures for boroughs in London.
Metropolitan Police Service - Crime statistics