The self-assessment questionnaires are not mandatory, and not all clients will complete the entire questionnaire - if a client is very unwell for example it could feel too overwhelming to complete, or a client may be having difficulties accessing their account (we will always help with this when we are made aware of any issues).
If you need more information before confirming a booking, we would recommend contacting the client to request that they complete the assessment in their account or to ask for further information. We have more detailed information about this scenario here.