Had mine a couple of weeks ago. Simple. Talked about elecsa, part p etc. Checked I had books, £2m public liability, calibration cert for tester. Checked I had cust complaints procedure (used the one they supplied in welcome pack and stuck it in a ring binder). Same again for estimates template. Chatted about insurance backed warranties and electrical safety register. Checked certs on install I was being assesed on. Drove assesor to the site (a cu change at my brother's flat). Checked if I knew how to use tester (zs at kitchen socket, rcd trip test and end to end resistance test from ring via lounge socket). Checked I knew the rcd trip times. Checked I was aware of earthing arrangements at the property. Random visual check on bathroom pull cord light switch. On way back home in car, tested my knowledge on associated building regs A, B, C, F, M, L1 etc. All they are checking is that you are safe and not an absolute numpty. Careful what you say about your install, as what can appear as a throw away remark, could be delved into and quizzed further. The whole experience was straight forward and informative. Took 3 hours total (around 30 mins on site). You find out straight away if you're in or not. Just relax, listen and enjoy.