The reason it is suggested (and it is not compulsory) that you bring a sandwich is that the company does not expect there to be sufficient time to join a queue for lunch. While I was there we had enough time to wander down to the staff restaurant but I understand that this is not always the case. You chose to apply for BA - they didn't track you down begging for an application form. I had to travel at my own expense, paying for hire cars, air fares, hotels and, bu&&er me, my own food but that was my choice. Words fail me sometimes.....