Welcome
enapace. A couple of points from my side:
1. Your profile does not show if you have Oneworld status or what class of travel you intend to fly, but be aware London City airport has no lounges, BA or otherwise, to enjoy before the flight.
2. For more information on ITA I would suggest looking at a few YouTube videos on the Matt's Planet channel. Here is a link for one that you may find useful as a starter: