The answers so far are pretty misleading.Thereu2019s actually no such thing in the UK as u2018official IDu2022 at all, unlike most of the rest of Europe.Germany, for example, has its Personalausweis, whilst countries like France and Italy have similar identity cards (which can be used to travel anywhere in Europe passport-free).Up not that long ago you didnu2019t need ID for anything.As recently as the 1980s you didnu2019t even need a passport to go to France or Belgium. (You simply filled out a cardboard, multipart u2018excursion cardu2022 at the departure port, and this was valid for short trips of up to 72 hours).What we call ID in the UK now, is entirely dependent on the requirements of the organisation or authority asking for it. Travelling domestically, or to Ireland (different airlines have different rules) you can use various IDs, like photo driving licences (itu2019s not that long ago that UK DLs didnu2019t have photos!!).Typically, today, when opening a bank account you need to present a passport (any country), EU ID card or photo driving licence as proof of who you are, along with proof of your address (original utility bill).There was a short-lived official national ID scheme card under the last Labour Government which would have served as a travel document, but this had not been rolled out to everyone when the Coalition abolished it entirely, six or seven years ago.So the answer is u201cget a passport or driving licenceu201d.AND you donu2019t have to wait till 18 to do either of those things - thereu2019s no minimum age for passports, and the earliest you can get any form of driving licence is 15 years and 9 months (though for some purposes learner DLs (we call them u201cprovisional licencesu201d) arenu2019t as good as ID as full licences.(ValidateUK and similar, are not official u2018IDu2022 despite what they seem to claim, but they are reasonably well accepted for the purpose of u2018proof of ageu2022 only)