Whether you are 'in' or 'out', I'm getting tired of immigration being the main issue for people - sure, it will have an impact, but brexit is not going to solve any problems with immigration that people perceive, and immigration fears does not seem to be to me a good enough reason to vote out. And voting in is not going to necessarily lead to a rush of immigrants.
We are not in the Schengen area, we have border control, and EU immigrants make a net contribution to our economy. Brexiteers often say they would like a Norway-esque agreement, which seems to me like all the problems (i.e., free movement of people) with none of the advantages other than being in the trade area (which we are already).
I just think there is more to the debate than immigration and it seems to me like it's been pushed to the front of the agenda to push more people to vote out due to fear.