I expect this is what will happen. A school will get one or two teachers good at the subject and will rotate those through all the classes. How and if that happens will be down to the foresight of the head teacher.
Given what I was taught in what was very embryonic IT classes when I was at school (it was called “Computers” and was run by the head of biology) - the skills I learned then (basically typing in databases on an RML 380Z) as well as the BBC Basic I learned myself - are pretty much redundant now. Maybe a foundation, but not much more.
If you are going to be teaching some kind of coding or coding practice, you really need to lay the foundations of ordered and logical instructions at primary level, and expect that secondary schools do more real world software engineering as the children there will be closer to the point where they will be seeking employment, and therefore need skills which are more current. How this happens depends on the nitty gritty of what the National Curriculum requires, how Ofsted interprets it, and whether it features in the league tables. I would say that pretty much every school has beady eyes on the last two criteria mentioned here and work towards those. Yes, I know, not what they should be doing, but that is how it is.