if you where legitamly born in the UK then then you don't need to do anything as it will state on your birth certifacate if you have lost this then you need to go to the registy office where you was...
Currently it's about 83 years for women, about 2 years lower for men. nonetheless keep in mind that severe illnesses, accidents, etc are also included. so don't you worry!
United kingdom is located in Western Europe, islands including the northern one-sixth of the island of Ireland between the North Atlantic Ocean and the North Sea, northwest of France