I am going to homeschool too (we have already started) I have worked as a advisor to homeschoolers so the first few years for me are fairly straightforward.) I am not too sure what I would reccommend for that. We are just writing every day, doing alphabet work, learning high usage words, and a range of practical maths activites. We are also going to as many places as we can to extend comprehension, working on social skills, and reading together (at the moment we are doing a series on Roald Dahl) We often will complete activites that spring from the book
However once your boy has the basics down pat you could try books from ESA Publications. I worked with them on a series (unrelated to these ones) and they are all written around the New Zealand curriculum.
They start from year three and go up to year eight in maths, english and handwriting. The best part is they only cost NZ$30 for a year’s textbook.
You would need to fill thme out a little with practical activity but they are enough to shape your teaching. For the rest, if the numeracy and literacy are on target, you can spend the remainder of the schooling just following his independent interests and reseach these together. One of the immense benefits of homeschooling
These textbooks are really reasonable, and have the answers in the back!
Hope that helps