How does Bernard’s behavior change when he learns that he is being sent to Iceland?

I assume that you are talking about what happens in
Chapter 16 when he actually ends up getting sent to Iceland, not the time before that
when it is only threatened.

If that is the case, the answer
is that Bernard completely loses his composure.  He hates the idea of being sent to
Iceland so much that he starts doing stuff like getting down on his knees and begging. 
He just will not stop until finally Mustapha Mond has to call for guards to take him
away and give him soma so that he will calm down.