Just a note that this is not a “Polaris Arrivals Lounge”. It is just signed “Arrivals Lounge” rather generically, and has some Heathrow signs to the side that say United and Air Canada.
Wanted to point that out so that you weren’t looking for Polaris branding. But the lounge is right outside arrivals to your left, and there should be no issue doing what you want to do.