Can't really say that I found anything too difficult - even the IMC course - some frustrations but nothing that I didn't overcome.
One lesson that I learned the hard way was how to open the throttle slowly after an incident in the Beagle Pup (beautiful aircraft) that I was learning on. While doing circuits in damp weather, I happened to open the throttle a little too quickly and got a bit of ice in the carb. The aircraft became airbourne on the fairly short runway, so no chance of landing back. I was mighty glad that the Pup, with flaps up, gave you a bit of buffet before the stall, so I was able to fly the aircraft at minimum speed while using oodles of carb heat. Eventually cleared the ice as I was turning downwind. The rest of the circuits were uneventful, but enjoyable.