As many people have posted before it takes time and effort to go through all the posts to glean information from this and other threads on British Airways recruitment. I did it and it took a few days, also invested in practice tools which I paid for. You have to put in plenty of preparation if you want to be successful, even in your written answers to the application questions. Take your time to get it right.
if you get invited to Stage 1 Aptitude Tests I recommend "assessmentday" and "skytest" websites.