Nothing is in an E number. E numbers are in things, to be pedantic. If you mean how can I tell I'm eating Calcium
disodium ethylene diamine tetra-acetate, have a look at :
http://www.foodlaw.rdg.ac.uk/additive.htm
Scroll down for list after the directives info - read these by the way and then wonder whats going on. . . Mineral Hydrocarbons in Food Regulations 1966 might raise an eyebrow or seven, though most stuff is covered by the Miscellaneous Food Additives Regulations 1995 (and respective Scotland variations) with specific cases for dried milk and other topical items also regulated.