As Badbadbunny said, IT is generally cross-curricular these days.
Computer Science is more academic. The gvt may have made it a compulsory NC subject, but there certainly aren't enough teachers to teach it.
You're lucky to have had it in primary - our primary (a relatively small one) is not doing much at all yet, and that's a maintained school not an academy.
Our secondary (academy) has just lost its one and only Comp Sci teacher. But to be honest she wasn't very good, so at least it leaves room for someone else to be recruited. Unfortunately they got no applicants when they advertised.
On the bright side, there are many ways for kids to get involved in coding and electronics outside of school. that's the way it always was before Comp Sci became compulsory anyway, and those routes will still be important during the transition period until enough new teachers can be trained.
The British Computer Society are now getting involved in teacher training, so numbers may increase gradually, so long as they're not all snapped up by private schools.