To reduce from three days at work to two when my eldest starts school?

OP I get it, my DH worked with a commute and lots of travel and there was no option for reduced hours, but he always had loads of leave and lieu days for travel so he could cover holidays (I am not a teacher). I had the local job and we purposely chose to live where we are so that I had virtually no commute, a support network and could be the on-call parent. Whilst I earned a decent living, DH was able to earn more and paid a higher share of the bills so all was fair.

You do what works for your family.

Well if you need to then do it but also consider the longer term effects on your pension. This is exactly why women lose out financially and men don't.

If that’s best decision go for it. Nothing is forever just keep under review. It’s a huge burden on you though he should appreciate.
If you have a few school options I’d look at them all. If there’s one with 7.30-5.30wrap around it would make life easier.
Totally left field but I do know teachers who have moved private and dc goes to school with them on reduced fees.
At end of day you know what is feasible for your specific situation. Good luck whatever you decide.

What do his female colleagues do? Is there a day he never travels for example.
I appreciate some jobs it’s totally impossible but if he was single he’d need to make it work. My dc’s friend at primary had a single Dr mum (no dad on scene at all) She made it work with calling in favours from other mums and a very pt ‘nanny’ she found on Facebook (firstly a young girl then a retired lady). I’m sure a lot of men would have pulled the I’ve a big important job I can’t possibly do school runs but she did sometimes.
Lots will depend on aftercare club - some may take as an extra if he can’t do school run due to work one week. Neighbour/another school mum. What is your backup plan if you need to be away on a course/too ill to drive to school etc.
Him just going to work v you doing all school runs and holiday childcare and working often leads to resentment and a very frazzled mum. But if it’s only option you have no choice but I’d at least want him to look at his flexible working policy and discuss with his manager.

Childminder?

You know what’s realistic but if he could flex and start later or finish earlier one or two days it would take some pressure off you. Has he checked his flexible working policy. It’s nice for him and dc if he does occasionally go to school.

Can't ever do a drop off on a single day of the working week...all year?

The Relationships board is full of women who have put themselves after their husbands super important job, and their kids, and the state of the house, only to find themselves with little of the way of pension, separated and earning significantly less than they should.

You can ignore commentators including me. I do really, really hope you are one of the lucky ones because from what I read on MN an awful lot of women are heartily regretting their actions.

My experience for what it's worth, the early years are absolutely relentless even with a supportive spouse who pulls his weight. Changing the dynamic of your relationship whereby you become the default carer, the one who always sucks it up though? That is a really difficult balance to change back.

It’s a danger that you end up staying in a job as hours suit (I did for years - not teaching)
But realistically there will always be teaching work and your school sound flexible. If he can’t drop off and pick up and afterclub is short hours then realistically it’s all on you until youngest is secondary age.
Are there any other options to 8-4pm wrap around eg childminder or different schools to consider. Those are very short hours.

Maybe between the pair of you both of you could drop enough hours to cover childcare?

I do think you need to acknowledge as a couple that it’s a huge burden on you doing all drop off, all pick ups and all school holiday care. Look at impact on pension - can you address this as a couple eg make additional payments.
Even a small change eg dh requesting flexibility to pick up once a week would make a difference.
If it is all you then I’d arrange hours to suit you.

Just do it. If your DH isn’t keen it would be worth asking if he can find any flexibility in his schedule so he can do some of the running around.

This - what is his plan to cover picking eldest up? If he's ill? Will he do things like get food in, take them to medical appointments?

it is not indulgent at all. Do what’s best for you and your family.

When we were doing this a few years ago, I recall that the rules were that the salary had to be equal to 16 (?) hours a week on minimum wage over a certain time period to get to the minimum pay requirements per week.

If you're a teacher you're likely to be on higher than minimum wage (although not that much higher for the added stress [I'm a former teacher]!) but you should still look into it properly just to be sure depending on how far you are into your career, where you are in the country (inner/outer/fringe/elsewhere weighting) and/or if you have additional TLRs to boost the "base" salary.

I think that info is relevant OP because if he is not offering to do any of the running around himself, his opinion on how you should arrange your work carries much less weight.

@jumpaboardapirateship what about your husband's role in childcare? Several people have you asked you that.

It isn't necessarily indulgent, as having more time away from work can help keep up with other things, like housework, admin etc, therefore taking the pressure off both parents.

Me and DH have always worked the hours we NEEDED to, as we don't want to be both be working full time for the sake of things.