You say DD has an ASD diagnosis but then also say DD is on the waiting list for assessment? Is she waiting for a diagnostic assessment for something other than ASD? LAs don’t normally diagnose.
Sensory assessments funded by the LA and NHS are often cursory in nature, I’m afraid. There should be some history taking (see below), there may be some questionnaires, and an even half good assessment will include some tasks for DD to do and the OT will make observations.
It can help to make a timeline of events, previous assessments, etc. Also think about making notes on things like developmental history, needs/difficulties (it can help to break this down and think about the different senses), likes/dislikes/what makes DD happy, what support is already in place, what has previously been tried, what has worked/didn’t work, what is needed but unable to be delivered, what is important to DD/you and what is important for DD, aspirations. If there are specific difficulties, such as with food or noise, it can help to make some more detailed notes on these.
It can also help to write a list of questions to ask (either beforehand or at the beginning) such as what assessments will be undertaken, what observations will be done (e.g. structured and unstructured times, with peers, with adults), how long they will spend with DD. Ask if the OT will make recommendations for the need for further assessments where they believe they are necessary - sometimes they do and sometimes they don’t.
Finish by asking them to ensure the report is detailed, specified and quantified and requesting the report is sent to you at the same time as it is sent to the LA - you may receive push back on this, but if you request it, it should be done.
Is this part of an EHCNA?
Just so you are aware, the LA is ultimately responsible for ensuring compulsory school aged DC unable to attend school receive a suitable full-time education. LAs will often tell parents it is the school’s responsibility, but ultimately it isn’t.