"As your child doesn't have a diagnosed condition as far as I can see, the DDA is not relevant. "
Londonone, I must totally refute that statement.
"The definition of ?disability? under the Equality Act 2010
In the Act, a person has a disability if:
they have a physical or mental impairment
the impairment has a substantial and long-term adverse effect on their ability to perform normal day-to-day activities
For the purposes of the Act, these words have the following meanings:
'substantial' means more than minor or trivial
'long-term' means that the effect of the impairment has lasted or is likely to last for at least twelve months (there are special rules covering recurring or fluctuating conditions)
'normal day-to-day activities' include everyday things like eating, washing, walking and going shopping
People who have had a disability in the past that meets this definition are also protected by the Act." (direct.gov.uk)
A child who has a statement for BESD and is being investigated for AS/ASD will most certainly be covered by the act.
In any case, wasuup is right, the DDA or The Equality Act are irrelevant initially, because regardless of disability, the school must follow the Code for Exclusions and inform the parents in writing of the reasons for, and the duration of, the exclusion.