You'll have all that time with your kids, without feeling guilty. I hated how much I've missed with mine. And friends who work in relevant professions say the kids with one primary carer at home are often the loveliest, most secure ones (obviously that doesn't mean none of the others are, I hope mine are!)
A lot of rows between couples are because they're both so busy and tired, and feel they're letting the kids down. You'll be able to prioritise each other, and can go for date nights while the grandparents watch them maybe (I'd feel guilty asking for that if they're already doing babysitting while I'm at work).
You'll be able to do all the reading, get all the costumes ready, go to all the activities, and make friends with other parents. Some of these mums stay friends for life. I always feel like I'm chasing my tail arranging meet ups.
You can prioritise your health, exercising etc. There's quite a few older women at my gym, and the ones who didn't work tend to look younger and be healthier, because they got to exercise more, sleep more, and didn't feel stressed/guilty/had fewer break ups.
I'm not jealous, honestly. I know I'm luckier than some, and we all can only do the best we can in our own situations.