Be honest about your status and if you're passively or actively job searching. Be open about whether you are interviewing with other companies or organisations and if so, what stage of the interview process you are in and if you have any pending offers. This gives the interviewer a better idea of how seriously you're pursuing other opportunities, how soon you're looking to make a move, and how quickly they need to make a decision after the interview. If you are interviewing elsewhere but the NHS is your preferred employer, don't be afraid to share that information.