Ad hoc childcare good enough for older children with sn?

[Raymondo]

I am a single mother. I have two children. One has severe OCD, the other has asthma and immune issues and spends a lot of time in winter off school. I am freelance, and currently desperately trying to a) get off benefits and b) become financially independent of my xh. My work is desperately important to me. Even though my kids are old - 11 and 13 - I still haven't found a good way of managing childcare that a) is affordable and b) can cope with my flexible needs PLUS the additional needs of my family. Xdh is lucky in that he has a mum and a sister who can help him out with our kids on the (v few) days that he has them. I don't have anyone.

As we're approaching winter again, I'm fearing yet another few months in which one or both dds are off and I am climbing the walls with frustration.

Who has any ideas for me?

Problem is, childcare usually excludes poorly dc. Flexible and affordable is a bit of an unusual combination as well, sadly.

Au pair. Work from home. Childcare swapsies with someone else. Renta-gran, ie an older retired person looking for intermittent work.

Childminder locally who doesn't mind adding in a big child occasionally for a bit of extra money. Over 8y don't count for their official numbers, so it might work.