If you need some help for resources for maths, I can point you in the right direction. Particularly if its secondary school (GCSE A/Level) material that you need.
Discussion
Just primary for now. But it would be great to prepare
So primary resources is not my speciality, but my kids are all in primary school and I can tell you what we've found useful. For 'structure', ie places that give a topic by topic breakdown of the typical things 7-11 year olds are learning in maths, I'd recommend:
piacademy (no need to subscribe - particularly the 11+ topic wise breakdown. very useful for structure - and challenging too)
oaknationalacademy. This should be great for structure too
https://www.thenational.academy/teachers/curriculum/maths-primary/units
I think its free for homeschoolers as well. But it should give you a good idea of what they'll be tackling at school in each year.
But for actually generating enthusiasm, I'd recommend the nrich website. For example: https://nrich.maths.org/problems/escape-castle
Or, for problem solving (vital skill!), maybe the primary maths challenge website. https://www.primarymathschallenge.org.uk/
Hope that helps!
All the best