Hey spanglepants, first of all, CONGRATS!!
I teach yr 3 and my DD was 26th OCt, spookily close to yours..!
I went of 2 wks before Oot half term, which was 9th Oct this yr, and I was 37+4wks. In all honestly, I would have struggled working any longer, and by this point I was getting lifts in and out of work as couldn;t fit behind wheel, but that could have just been me! DS was also a bit early too, came on 21st so only had a wk off before he arrived anyway.
I didn't have a class in Sept tho, head took someone to do my mat cover for the whole year, and I did PPA for 5 wks, as decided it would be a bit disruptive for a class of new yr 3's to have a new teacher so soon into the yr, is this an option you could suggest to your head, as could be the same with you and little ones too. However we are a big school (4 form entry Junior) so quite a big PPA demand!
I'm going back in Sept, but 'officially' July 28th so I get paid in summer

Oct is a really good time for a 'teacher' baby IMO!
Hope this helps!!!
xxxx