I think the school is trying to resolve the problem between you and them without involving more organisations.
The school wants to make sure that all the additional measures are in place (and not working) before they look at why things are still not working (if the child doesn't keep progressing at the same or improved rate).
If you ignore the school for to long, and they want to make a big deal about your attitude to the schools attempt to resolve issues, there is an educational supervision order which a Local authority can apply for. To be fair, you don't sound like the type of person who would need court involvement, so not a worry.
What is obvious (based on what's in this post) is that you want a few ideas about different options. Earning the income is important to you because it allows you to give your children the things they want, and more if you can. You have obviously put things in place which allow you to get the income you can.
Keeping a child up till 9pm is not practical, the child will be tired and not able to concentrate, so the exercise counter productive.
Can you get a Granny or Granddad involved, perhaps a few times a week, who can go through the reading with your child?
Could you perhaps look for a child minder who has teaching qualifications, who could pick the child up from school and have the child for 2 hours 3 times a week. The child minder can focus on the reading and other home work.
Dyslexic children need additional stimulation to give them the most chance possible now to get as much skill as they can get to prepare them for their life as an adult. All the time you loose now is lost forever. Children learn the most and the quickest as a child.
Is there an opportunity for you to spend a few hours on the weekend reading with your child? Children like to please their parents and do things that make the parent happy. You should be the person that manages the child's care and who the child looks to to to feel loved and accepted. You should be the child's guide in life and the child's role model. The au apir is unlikely to feature in the child's life on a long term basis.