Even 'corrective training' is a thing of the past now.
What can you expect from PT? Well, to get hot, sweaty and out of breath I suppose.
As long as you have been doing your own program of fitness training in your own time between training weekends you should be OK. Nothing carried out as part of your syllabus is out of reach as long as you train between weekends (and I don't mean one night a week, try three or four times a week with a realistic training program, try asking PTI's at 4Div RTC or your own unit for these).
The PTI's do vary, but there are a regular 'core' of PTI's that turn up most weekends, they are VERY professional and take your fitness training and assessment seriously. They will not 'beast' you, but training and standards are set high so you will be pushed hard, which is only right and proper for a career in the military