The taxed savings seem to me to be a no-brainer; putting (some of) that money into the offset effectively earns you your mortgage rate of interest, tax free, not to mention reducing your monthly minimum payment.
The cash ISAs are a harder call; taking them out of the ISAs would mean you have to start again from scratch should you decide later that you do want some ISA savings once more. That said, a 2.19% difference in interest on 28K is 613 per year; that will add up quite favourably over the remaining term
The kiddy savings accounts are also difficult; if they're in your childrens' names, you might find it difficult to access them.
In these troubled times, do also bear in mind the 50k FSCS compensation limit per banking group - make sure that your savings are diversified.