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.
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.