From the website of the Home Office Identity & Passport Service (surely facing an imminent name-change):
Both Parties that now form the new Government stated in their manifestos that they will cancel Identity Cards and the National Identity Register. We will announce in due course how this will be achieved. Applications can continue to be made for ID cards but we would advise anyone thinking of applying to wait for further announcements.
Until Parliament agrees otherwise, identity cards remain valid and as such can still be used as an identity document and for travel within Europe. We will update you with further information as soon as we have it.