The PTA comments are weird. When dd was at primary, most of the PTA meetings were in the evenings, I think the members were a mixture of WOHPs and SAHPs. Men as well as women. I didn't hang around that long though, as I found it very cliquey - more like a social club to be honest, with a bit of fundraising on the side. It is a very active PTA, but the funds they raise are just a drop in the ocean as far as the school is concerned - though of course, every little helps. Personally, I prefer to give my time as a school governor instead.
No-one had yet answered my question - honestly when you are working, how do you manage children being sick (one of mine has just been off school for a week), school holidays, INSET days, school meetings, appointments? Do you have to take the time unpaid?
DC sickness - no underlying health issues fortunately, so this isn't a regular occurrence, but usually I'd work from home or take leave if dc needed a lot of time and attention. DH would also do some sick days, or we would both do half days etc.
School holidays - I get just over 9 weeks of paid holiday, including bank holidays, so I can cover a lot of the school holidays and dh can cover most of the rest. We do occasionally do childcare swaps with other working parents and my parents are happy to help out if we are stuck. I'm also able to work at home if needs be. We have also used holiday clubs in the past, but only when dd has actually wanted to do them - we never had to go down that route for childcare alone.
Inset days - as above. They're usually tagged on to school holidays around here, so don't really notice them.
School meetings - most important meetings are in the evenings in my experience, but for the odd assembly/open classroom and other stuff happening in the school day, my job is very flexible so I would usually just go and then make up the hours as and when. DD is at secondary now, so these things don't really happen any more.
Appointments - just take the time off and make it up later.
I work full time but have lots of parents in my team with childcare responsibilities. I bend over backwards to accommodate them because I know that they will appreciate the flexibility and give a lot back. And yes, quite a few work school hours, including some in well paid professional jobs.
OP, I think it's fine if you choose not to work. I wouldn't choose the life that you have chosen, but as long as you and your dh are both happy with your family set-up, then you really don't have to justify your choices to anyone.