You have DC with SEN, and have chosen not to work.
Oh look, here comes @NikeDeLaSwoosh with another unpleasant and judgemental comment about raising a disabled child.
Many employers pay lip service to offering flexible working for parents and carers but when it comes down to it they don't follow through. It's a bit like how many people in this country pay lip service to how important equality and accessibility with the unspoken proviso of that importance vanishing once it causes any sort of inconvenience or feeling of injustice to non-disabled people.
It is very difficult to find childcare that can cope with a child who has complex needs and, if you do find one, it is not uncommon for it to cost more than other childcare which tends to limit your choices if the childcare is going to cost more than you earn.
Even the most understanding of employers will have a breaking point, they're trying to run a business and need reliable staff. If someone is being called to come and collect their child at short notice several times a week, or is late several times a week, or has repeated childcare providers serve immediate notice then they are not reliable.
There is a proven link between disability and restricted earning potential, this extends to those who care for disabled people including parents of disabled children. Being a carer impacts your health, your emotional well-being, your free time, your career, and your income.
Now multiply that by two as the OP has two disabled children.
Instead of making snide comments about it being s choice not to work, give your head a wobble and think about the barriers to employment faced by the OP and others in the OP's situation.