I used a childminder for school runs until they were both at primary. Your LA may help with expenses. I’m not familiar with the system in England, but there should be support from your local Social Services for you as kinship carers, regardless of whether you qualify for a fostering allowance.
The kinship care team here can refer children for play therapy, arrange extended pre-school nursery hours, and give you names of local family solicitors experienced in residence orders, adoptions, etc. You may find that your DN come under the umbrella term of “care-experienced”. This is simply because she is not in the care of her parents. It can open up more support for you in the future, with progress reports and care plans both in pre-school setting and later in school.
I can fully understand why this is hard for your DH, and it saddens me to read the harsh responses. We have never regretted taking in our dgc, never even for a moment. But it changes relationships and plans for the future in ways that are sometimes completely unforeseen. It’s important to acknowledge negative emotions to each other as pp described.
I have support from outside the extended family, from nursery, school, from kinship care group with links to other organisations, Barnardo’s as the dgc get older.
Personally, I would get as much support as possible from SS, schools, etc, and then call on extended family to plug the gaps. Make keeping your job one of your top priorities.
I wish you all the best