If you’re living in Australia, you can apply to extend your British passport for 12 months.
This covers Adult and Child passports, without any extra fees.
Source: https://www.gov.uk/get-an-emergency-passport-extension-or-child-travel-document
You can enter the UK with an extended passport.
Other countries and territories that accept extended passports: www.abcdiamond.com/british-passport-12-month-extension-validity-by-country
You should check that the country or territory you’re travelling to will accept extended passports – phone your nearest British embassy, consulate or high commission.
Eligibility for a 12 month extension
All of the following must apply:
- you’re outside the UK
- you have a red passport
- you haven’t already applied to renew your passport
- your passport expired less than 6 months ago or will expire in the next 3 months (or in the next 7 months if you’re in oroing to a country or territory that says you must have 6 months left on your passport
- your passport has at least 3 blank pages