Make sure that you rehearse 'what to say about yourself and what type of experience you have had'. How might you deal with a difficult passenger, customer. Come along dressed in a suit, make up in moderation, as so jewellery. A good measure is to ask mum or dad how you look. The day is to assess among other issues what you might look like in a uniform, therefore wear a uniform suit.
Spend sometime on the web looking at all BA offers, class of travel, routes, new ones, Oneworld, future plans and the general aviation situation. You will not go wrong using this site to read up on the many threads. Ignore some of the BA stuff on this thread as they spend much of their time winging and moaning about T & C. Use your familly and friends to speak about yourself briefly, do not be scared, be yourself. Do not make up things and when you practise make sure those listenning fully understand you. Remember just because you know what you do others do not. Think of what you do and list every bit of it to paint a picture of the perfect you and how we cannot afford not to employ you.