U.K. passports are valid for 10 years for adults and five years for children under 16 years of age. A child passport can be extended for another five years once the child is 16 years old, notes PassportVisasExpress.com.
The UK government states that the application process can take up to six weeks for first-time applications and three weeks for other types. There is also an urgent service that can provide a new or renewed passport in one to three days. A passport application can be completed online or sent by mail. There are also independent agencies that can provide assistance to passport applicants.