Inset is just teacher training rebranded as it doesn't just involve teachers anymore
If you're pure TTO with no extras at all then no, skip them unless they wanna pay you the overtime as you'd be working/training for free
I've emailed HR and it turns out they have no idea what the definition of a 'term day' actually is and were struggling to comprehend that I wasnt asking 'what does TTO mean?' and was seeking a clarification definition of a term day.
They suggested, based on an NEU point, that it was when schools are open, but I pointed out they are open during the holidays too (for full time staff) but these arent considered term days.
All in all it seems they couldn't answer my question.
HOWEVER....
this appears on our city council website on their term dates page:-
"The school year starts in September. There are 195 school days in each year (39 weeks). Pupils spend 190 days (38 weeks) in school each year; 5 of the 195 days are reserved for training teachers and support staff."
Which suggests that the inset/teacher training days are already built in to 'term time' and thus must be attended as per our contracts if TTO.
So it would seem that there isn't actually a definition of what a term day actually is (that HR are aware of anyway), which seems a bit odd in a legal sense but hey, it's not my problem!