The interviewers ask this question to hear what qualities you will bring to the NHS and how you will benefit them if hired. Now is your chance to highlight your best characteristics and experience, showing the interviewers you have all the qualifications they require.
It is best to review the job announcement before your interview and highlight the qualities, experience, and education the NHS seeks in their project support officer. Then, focus on using those keywords in your response. When describing how you meet their job requirements, the interviewers will see that you are a highly qualified candidate.