What we did was look at what we wanted in terms of support and what was needed. It's not about looking at what's offered but at what the parents feel their child needs. You argue the provision offered when you get the draft ehcp.
We made a list and put the most important things first and stated our wishes regarding each heading. ie communication, physical development, social integration, support and so on.
So for communication we explained what ds's current capabilities are, what we feel has been failing, what we feel he can achieve, where he can receive the correct help (different school) and so on.
I underlined headings to paragraphs and kept it visually more readable (it went into 6 pages) as it's important your main wishes and facts are stated clearly.
Our main headings were communication, cognition, emotion, social, physical.