sure start used to do "stay and play". You meet people and the kids get interaction and stimulation. Does this still exist?
I would have gone crazy if I hadn't gone out for large chunks of the day. Do you have friends in similar situations? Coffee mornings gave me a sounding board to offload my frustrations and gave me a break from the kids as the kids played.
Do you let them watch cbeebies? I suspect not, as research says tv isn't great. And you seem to be trying so hard to be the perfect parent and researching everything. Well tv isn't bad in small doses, and it saves your sanity. My kids learnt quite a bit from carefully chosen programmes which stimulated their curiosity.
Don't try to be the perfect parent. Relax, Be a "good enough" parent. Nobody is perfect.
Your children want quality time not material things.
Give up work or use childcare.
What about setting a timer for ten minutes to get chores done in small chunks so that when the buzzer goes off your 2 yr old knows that you will be available again?
Research activities to entertain young kids.
If DH doesn't want the children to go to bed so early, then let him take over responsibility from 7pm completely. Then it's his choice, but you need to switch off in the evening. This isn't a desire. It is necessary to stop you from going under. If you are not depressed now, you will be soon unless you make big changes now.
Relax and DON"T TRY TO BE PERFECT. You will make them anxious if you are constantly striving for this. It is not possible.
If you give up work, less materiel things will not make them unhappy. If you use childcare this will not make them unhappy. Do what will make you the happiest. As flow said. A happy mummy makes happy children.