I recently did a similar itinerary, but with a same-day connection at OSL. Unless I missed a turn or something, it's not possible to get to the lounge on arrival.

Still, My LHR to OSL flight arrived at a domestic gate and buses were required to get passengers to the international terminal, so perhaps it's different if entering the international terminal via the jetway from an international gate.

But regardless, if you have checked baggage, you will need to claim it, clear customs, and recheck it, which I believe rules out any chance of access to the lounge.