It is a bit crazy that not all teachers will have been jagged by the start of the new year. I thought all over 18s should have been given the vaccine by mid July, so 20s/30s should have had theirs by the end of June, meaning their 8 weeks would be up over the summer or shortly after the start of term - though maybe the SG didn't meet that target? It can't be long, anyway - and I think the mRNA vaccines are fine to give at a shorter interval too, if the worry is catching covid in between the two jags rather than building up the full potential immunity between jags (which is presumably the worry here). We do seem to have had a big slowdown of vaccines from early June (?) though, which can't all be caused by the necessary 8 week delay, or else there'd have been a pick up again from the end of July.
I don't think there should have been prioritisation of teachers initially though (other than if they were CEV or CV so eligible for a jag earlier than their age group). The JCVI always said that the aim of the vaccine programme was to reduce hospitalisations and deaths, so prioritising those more likely to need hospital care (i.e. older people first, and their carers) was really the only way that could have been done. You may think it wasn't properly managed if non-frontline NHS were included in the first round (though non frontline NHS are often critical to the work of the front line folks), or disagree with their aim, and think it should have been to stop as many people catching the disease as possible. But we are where we are and I don't think it's fair that children are subject to further restrictions for maybe 6 weeks- maybe more - because the government failed to vaccinate enough of their teachers by the start of term.