What I don't get is that other than the immigration issue they really benefit no way unless I am mistaken. They would have been better to identify that as a key thing and approached brussels about some way to limit immigration through the EU. Or is that not possible? I would imagine they would have been able to use exiting the EU as a big stick in negotiations.
I believe that the EU is stronger than the UK and the EU intends to make Britan sorry for it's lack of forethought and vision.
The thing about the EU is that it is a huge bureaucracy. So it would be a huge and difficult process to get an exemption for immigration, possibly even impossible. I think it is a true lesson of what happens when you make such a decision political. It is also a lesson of what happens when they lose touch with voters. The PM recommending people vote against Brexit, would have just make people who are against the PM and the government, vote for it.