Only one interview at Oxfam office. Very conversational and informal interview. Relaxing, no hard technical questions, kind of get-to-know-you interview type. Casual or business casual dress is ok. Wearing suit to this interview would feel very awkward. Try to be relaxed and show your genuine interest during the interview process. Keep in touch with the interviewer after the interview. Maybe they don't accept you for this role, they can call you later for another role. So stay tuned and be ready.