Be careful with SENDIASS. Some are good but too many repeat the LA’s unlawful policies.
Reading the SENCOP and Noddy guide will help.
You could go through the reports you do have with highlighters. Highlight all DC’s special educational needs in one colour and all the provision to meet the needs in another colour. Each need should have corresponding provision. This will help when you get the draft because all the needs should be in B and all the provision in F.
While you are doing this, make a note of any vague and woolly wording (e.g. “access to”, “or equivalent”, “opportunities for”, “as appropriate”, “would benefit from”, “regular”, “up to”, “would be useful/helpful”, “such as”, “e.g.”, “etc.”, “as required”, “as advised”, “key adult(s)”, “small group”) or anything the reports have omitted. Then go back to the LA and report writer(s) requesting they make the reports detailed, specified and quantified. If the reports are vague and woolly, the EHCP will be too.