Hello OP, I've changed my name because it's a bit outy but thought my story may be helpful.
I had a first lucrative career for about 15 years and then married a workaholic, high earning man. We are still very happily married 30 years on. I went back to work at 43 when my youngest was settled in reception. Although I had a good career before dc I had no degree and no professional qualifications. I had to think laterally about what might suit and I returned for pin money and because I was bored and taking on too many voluntary obligations.
An opportunity to become a casual invigilator came up at a local College and I did that for about 6 months until a part-time, low grade admin role came up in HR. It was 18 hours pw and I started by doing 4 4.5 hour days around the children. Holidays were good and after the first year I went term time only.
I enjoyed the work and gave a higher contribution for my grade and after two years was asked if I'd go full-time, two grades higher. I agreed subject to them.sponsoring the CIPD qualification which they did. The extra money went towards employing an au-pair and we had 4 over the next 4 years until dd went to secondary school. I stayed there for 9 years and was a Business Partner when I left. I moved sideways to a more complex local organisation, becoming the Deputy Director about 5 years ago and am now the Director. Once I could work beyond 9.15 to 5.45 as became older teens (with lots of extra curricula activities) my career started taking off.
Apart from personal fulfillment the additional benefits have been that it actually intellectually invigorated my relationship with my DH, brought me back into contact with the real world when my existence would otherwise have morphed into a privileged bubble, and has provided a better role model for the DC who had to become a little more self reliant than some of their chums who could rely on mum to waft into the school office at 10.30am with a forgotten clarinet or gum shield.
Significantly I transferred about 10 years of pre DC pension and 9 years post DC children into a final salary pension scheme and sadly some of the DC's friends' parents separated as DC hit their later teens - usually due to the DH meeting someone younger and who had more to talk about than: the DC, the tennis club, who they had met for lunch and local property prices, etc. Sadly often women in their mid 50s who hadn't worked for 20-25 years and who had become completely unemployable, even in a minimum wage job - often the same women who were a little sneery when I took that min wage job 15 years earlier. It's really rather sad, they have had to move out of the beautiful family home to modest houses are with a few exceptions very very lonely and rather bitter.