I applied on January for the cabin crew talent pool (Heathrow), received an email 4 months later to complete the online assessment, I'm now waiting for their response. The assessment was fairly easy, you just have to remember their company values.

Submit application on website, attach cv. Once accepted, complete the online assessment within 3 days of receiving the invite. (Maybe Psychometric style and situational judgment) British Airways do change the assessment types so bare in mind.

Starts with a group of about 25 people, then have to do a height and reach test accompanied by reading out a script to one of the interviewers to prove your english speech. Then have a group task with half the group to see how you interact with others. Then half the group are sent home and the other half go through to individual interviews.