Use of Passports

In the event of 'no deal', new rules will apply when travelling on a British passport to many European countries and some people may need to renew their passport earlier than planned to ensure it is valid. This will apply for travel to the 26 countries in the Schengen area.
There is a tool and guidance already online at GOV.UK  to check whether a passport is affected.
 
Specifically, under these new rules:
  • You should have at least 6 months left on your passport from your date of arrival. This applies to adult and child passports.
  • If you renewed a 10-year adult passport before it expired, extra months may have been added to your new passport's expiry date, making it valid for more than 10 years. Any extra months on your passport over 10 years may not count towards the 6 months that should be remaining for travel to most countries in Europe.
If you hold a Crown Dependency (Guernsey, Jersey and Isle of Man) or Gibraltar issued British passport you'll also need to comply with the new rules.
 
For those who need to, the easiest, cheapest and most convenient way is to renew online.