Received an update from passport office earlier
"UK passport validity rules in Europe have changed. You may need to renew earlier than planned. Check entry requirements at www.gov.uk/passport-travel-advice "
I think what has changed is your passport must be valid for at least 3 months after the day you plan to leave
From website:
"If you are planning to travel to an EU country (except Ireland), or Switzerland, Norway, Iceland, Liechtenstein, Andorra, Monaco, San Marino or Vatican City, you must meet the Schengen area rules.
Your passport must meet 2 requirements. It must be:
less than 10 years old on the day you enter (check the ‘date of issue’)
valid for at least 3 months after the day you plan to leave (check the ‘expiry date’)"