So I should focus on my breath AND an inch behind my forehead whilst meditating, and not just focusing on my breath moving in and out?

Yes, focusing on both your breath and a specific location an inch behind your forehead is recommended during meditation for enhancing your focus and concentration. According to Andrew Huberman, including this additional focus point can help you better engage the networks in your brain responsible for focus. The practice involves expecting your attention to drift and using those moments as cues to refocus on your breath and the spot behind your forehead. This not only helps improve focus and concentration but also offers benefits for memory and sleep 1.