Ginny
It sounds as if you were offered a short notice appointment.
For others reading this, you do not need to accept these, the Assessment Providers are required to give claimants seven days written notice of an appointment. However, once accepted it will be treated as a standard assessment.
Have a look at our ESA Claim guides there are sections covering the assessment and the questions you are likely to be asked.
www.benefitsandwork.co.uk/help-for-claimants/esa1 Gordon