A guide/some links to websites which can help you find out if the ingredients in some foods are vegetarian or vegan friendly :
The Happy Cow website has an A-Z list of items that may contain animal ingredients and/or by-products of animals.
The “Is It Vegan ?” website is a searchable database where you can find information on food and other products which are vegan friendly.
Real Food is another vegan website that has a list of E numbers and a description of what is in them.
The Food Intolerance Network is an Australian website with many factsheets and lots of information about food additives, ingredients and allergies.