It's f...... Stupid. Up north here there are some dopey signs that try to tell you there's an exit in 3/4 of a mile for example. ... Takes a few goes to read that sort of thing at speed.
Having said that, I generally talk in miles and feet, being near the 40 mark and having parents near the 80 mark. I missed the whole metric really.
cm and mm I do like.
Of course, there were also Irish Miles. Honest. Look it up.