Hope you feel better soon.
advice I got here for my daughter who applying, though not to foundation, was to read carefully the code of conduct and 1st day competency document. The skills and qualities are clearly layed out. Think about your work experience and anything you have done at school and how they can be used to demonstrate those qualities. Once you have read those the essay will be easy. Read over what the foundation year covers, that should help you discuss that aspect. Use a skill you have that the course can help you develop. You are demonstrating you have the skills but acknowledge there is ways personal development and learning
Good luck. More daughter is also unwell and struggling to prepare for an interview alongside her school work. Shows your resilience!!! .