At this age and with this age gap it's really difficult to do artsie stuff, or cooking, and so on, as both children need a lot of attention. As you've found! So don't feel bad about not doing it. The bet time I found for doing that sor tof thing with my elder was when the younger was napping.
But what you're describing is why I suggested AE. The children are off your hands for a while - the creche staff will mop up, change nappies, comfort and entertain for a couple of hours, while you get some mental stimulation and adult company. A real breath of fresh air.
You don't have to do a formal qualification, or something that will 'lead somewhere'. I did things like pottery, painting, sewing, mosaic making. The children still wear some of the clothes I made, as does dh . Some of the pottery I made is on display in the living room (or at least it was until we moved house, and once we have a living room again it will go up on display again). Real and pleasing reminders of life and achievements outside these four walls.
When I started the very first course, ds was 12m and I had never succeeded in leaving him in a creche for more than 20m before. I couldn't believe it that the staff didn't need to call me for the whole two hours, and when I went to collect him he was contented. Boy, did I hug those ladies! It was such a liberation!