British passport guidelines and help should be useful if you want to apply for a passport or renew an existing one all the links are relevant and divided into those of particular relevance to British expats and those of a more general nature.
There is also information on what to do if you lose your British passport along with costs and likely service times.
For British Expats:
Renewing a British passport if visiting the UK. You’ll need to be in the UK for 3 weeks to renew a British passport, or 6 weeks to apply for a first British passport, if you’re visiting the UK.
British Citizens Overseas applications and renewal of British Passport. Get the forms, prices and application details you need if you’re a British national and you want to renew or apply for a British passport from overseas. This page has a built-in Q&A to point you in the right direction.
Report a lost or stolen British Passport. You must tell Her Majesty’s Passport Office as soon as possible if your passport has been lost or stolen.
For all British Citizens:
Apply for your first British passport. Includes details of who is eligible to apply.
New online service for British passport. You can apply for, renew or update your passport and pay for it online. You’ll have to print out a form at the end. This service is in Beta mode.
British passport application form. Fill in the online form to request up to 5 passport application forms in English or Welsh.
Passport photo requirements. You must make sure photos for your passport, driving licence or visa meet all the rules – your application might be delayed if you don’t.
Eligibility for British Passport:
Here is a link to some guidelines on eligibility for a British passport. You can apply for a British passport if you have British nationality. But there are some circumstances where your application can be refused or your existing passport can be retained.