To help you plan a response you should get a big sheet of paper and list the essential requirements from the job description and any person specification and the advert, then for each one think of one or two examples of how you can show you have these skills/experience/training via education, exams, training courses, and more important doing things on the job or in your spare time like helping at the old peoples home or doing knitting club paperwork or even looking after a family/household budget.
Then write it all up showing that you meet most or all requirement's.