Re the idea that the Pakistani community don't integrate due to their belief. The book below on page 39 suggests that of the households where the main income earner is from the non-white community in Scotland (which it says are mainly Pakistani, Indian or Chinese) a full third of them are married to white partners. Yes really religious people tend to marry into their own religion but that would be the same for all religions and not just Pakistani Moslems. If about a third of Pakistanis main earners are married to white people then there must be a fair bit integration going on - and of course you don't need to marry into the white population to integrate into society.

https://books.google.co.uk/books?id=6ck5vAD3no4C&pg=PA39&lpg=PA39&dq=scotland+mix+marriage+pakistani&source=bl&ots=-XqbbNl5Vu&si