My understanding from the families I have worked with is that Kumon provides more practice at the child's skills - bit essentially is an additional curriculum of which the child gets homework as well - so thats on top of the work from school. It's not adjusted for the child's individual needs - but a typically developing child might get benefit from the extra practice.I believe they get booklets for their grade level and work their way through them.

It's not something I recommend for parents of children with dyspraxia or other difficulties. Id also advise an individual tutor who can liaise with the class teacher and ensure the work is directly related to what is happening at school or your child's specific needs. A university student studying teaching or a related course may be another option if an experienced teacher is a bit expensive for you.

The OT may also have some advice about related strategies as well. Good luck! It's hard watching your child struggle.