No, never heard it or used it but there are loads of slang ways to say it, every region will have different ways. I did hear 'sack off' used to mean 'playing truant' when I was growing up sometimes. People would have said something like 'I think I'm gonna sack off maths this afternoon, I can't be bothered.' The most common way to say it where I lived was 'to wag it' or 'to wag.' Meaning to not go to class. Where's such and such? Oh he's wagging it. My dad informs me where he grew up they used to say 'to twag it.' 'Play truant' is I guess, the official way to say it in the UK. If a newspaper report were talking about this topic, that would be the phrase they would use. Talking about compulsory education here, you can't play truant from university. 'Skip class' is more American although it wouldn't sound out of place in the UK. I've heard it used in the context of college in the States as well as high school. 'Cut class' would sound strange in the UK. There are probably new ways to say it that have come about in the ten years or so since I left school.

You wouldn't hear 'sag off' in the US, but you would hear 'skip/cut' class. 'Truancy' would be heard more in the context of school written policy regarding cutting/skipping classes.

Thanks Angela

No, In the US, we do "play hooky" which means the same thing.