I would advise to play safe. Obviously if you are getting an experience letter prepared from your company for PR application, they would know you'll move out. In my case, I informed my line manager that I will be going for 2 weeks and will be back to work. My wife will stay there for a total of 2 months and will be back once she receives our PR cards. We will then stay and save for another 2 to 3 years before we move permanently. He never asks me because he knows I am not leaving anytime soon.Bear with the nosy HR head until you have got your COPR because God knows if CIC needs to check your information with the companies you have worked for.
I got the same symptom, happy and determined at first, but gradually grew worn out and demented.