Hi, welcome to the site. This is an indepth project where each point that you've listed needs researching.
Search page - enter words from the assessment criteria to search.
How you layout the booklet is what makes it yours :)
Sources of information that may help with this are a level 3 handbook -
on amazon.co.uk
Food.gov.uk -
nutritional guide
https://www.vegsoc.org/
http://www.vegansociety.com/
Drinking poster from HydrationCouncil.org.uk
Healthy start programme & vitamin supplements for children - NHS.uk
http://www.diabetes.org.uk/Children-and-diabetes/
Coeliac disease and lactose intollerance
From Ireland -
http://www.dentalhealth.ie/children/
Cross infection -
http://www.silkysteps.com/forum/showthread.php?t=13717
Food hygiene on Bupa
Hth, enjoy the site