Frustratingly, I wasn't able to talk to the GP today as she rang earlier than stated. And when I rang the surgery was told "they only try once" so now have to wait until the 14th October to talk to someone about my result. So brassed off. Anyway, got the receptionist to at least give me the reference range for the cortisol levels and it is 250-650. I have no idea of the units they're measured in though. I've been trying to find information online but all the ranges seem to be in far smaller ranges, so I guess the unit of measurement is different. I'm going to request a printout of my results too.