Given that the other OW lounges are closed (CX opens after 9 pm/ JL closes by 3 pm), you're left with the BA lounge which isn't worth writing home about. They have drinks and snacks, but that's about it.
Be aware that status and premium passengers on the BA afternoon flight usually board from the lounge making it quite noisy. With the A380 flight in the evening it gets rather busy as well.