Hi AtYourCervix
Firstly, I just wanted to pick up on the sentence:
"You need to provide evidence that your DD is unable to access the curriculum without one-to one assistance and a statement so the more evidence the better."
Statements of Educational Need are not just about 1:1. There are many many children who do need a Statement but for whom 1:1 (either on its own, or in conjunction with something else) is not appropriate.
There are several stages to Statutory Assessment. The initial letter is just your 'flag' to the LA that you think your DD has enough needs to warrant a Statutory Assessment.
Once your letter reaches the LA, they will respond by contacting you for your initial views, and also the school, etc. So, you will have the opportunity then to give a detailed report of your views.
So, you are well within your rights to send reports and a detailed summary of your reasons for applying. But they will still want you to give those things once they write to you.
I took the approach of writing a 'potted history' of DD, with a summary that listed current support, who was involved with her and my reasons for thinking that a school couldn't meet her needs from within their own resources. Because that is the criteria for a Statement.
However, the LA have to treat all requests the same, so you could just as well send a piece of paper with your name and address on it, with the sentence 'give my DD a statement, 'cos she needs one.' and they would still have to follow the same procedure as if you have sent in a ring-bound, professionally printed report.
(I wouldn't recommend the letter with 'give my DD a statement, 'cos she needs one.' though
)