Sorry, going to derail slightly first, which waiting lists are your children on at the moment? If you need autism assessments, please contact your GP and ask them to refer you to Paloma Health through the right to choose pathway- they assessed and diagnosed my kids within 6 months.
Also, care ADHD are doing assessments for £299 privately.
I don't think you're wrong at all in what you're doing.
My eldest and middle are both now in receipt of their disability benefits now- DD is 17, so I have nothing to do with them, I just advise her that she needs to meet some of her own costs so she needs to have some money aside.
My sons, which goes to me- pays for a lady who will help us achieve activities I wouldn't manage because of his SEN otherwise. So swimming etc, the rest goes into savings, or meeting his direct needs (like hearing tests we've been waiting for for over a year so decided to go private) the Wagon we've upgraded to because he needs to be in a pram but bites his brother in there. The specialist communication courses we were re commended will be paid for out of it, as will additional childcare that enables me to attend.
I am paying off some of my Credit cards also, but those credit cards were used to purchase have his SEN high chair at over £700, and his Ipad that I purchased solely to put a communication app on- that also cost £300... if they weren't run up to try and meet his SEN needs, I wouldn't be touching his money for it. How did your partner get his CC debt?