As a data point, flying out today. The eGates are all closed and this is the line for exiting the EU. It took 32 minutes to clear.

the lounge is way before passport control so you would have no idea what you’re getting into if you went to the lounge.

It is oddly super variable, some days at the same time there’s no wait and some days at the same time there’s a long wait.

The only consistent is GroundForce (the BA handling company) will never wait or assist you.