Starlight,
You mention on another thread that you want this for your HE son - but he is currently in school? And on another that you want to move him very rapidly from P levels to Level 2, and are considering HE / flexi schooling to do this?
It's probably worth thinking through what you want, and why you want it - and also the context around assessment in school. Level descriptors - P levels and NC levels - are widely available. In the old APP documentation, you will also find exemplar portfolios of work by children working at different levels that have been provided to aid in levelling.
The point, though, is about context. I wonder whether your hope in this is to be able to 'tick a lot of the boxes' while working at home with your son, and then use this to show the school that he is working at a higher level than they have assessed him at? Bear in mind that, for many of the assessments to apply, the child has to be working independently, in a situation where there is choice and freedom, a significant time after the point of direct teaching, and evidence has to come in a variety of different contexts. Saying that you child can achieve those thing when working 1 to 1 in the home environment with no other children around and a parent hovering is not necessarily evidence that the child is genuinely at that level IYSWIM, and the school may be of the same opinion.
Definitely worth talking to the school, asking to see his CURRENT assessments, and then talking with them about any items that you KNOW he does very well, totally independently and a long time after you have workied with him on that area. That will pinpoint any areas where he is not showing his true ability in school [a similar discussion about my DS early in his school career indicated the extent of his school-inbdiced selective mutism] and, if there is a pattern of such areas, perhaps suggest a specific weakness or a way forward.