As Andy said, tell him the Examiner what you are doing, particularly if your nav has gone a bit astray. I wrongly convinced myself that I was off track, by looking at the wrong disused airfield, and flew to it, but told the guy that I was in error, and was going to fly back to my last known position and regain my track. He was happy with that.
You may it may not be asked to do everthing on the list. For example, if the Examiner likes your PFL, he may not bother with a glide approach in the circuit. Try to fly precisely, but don't sweat too much at the time if you wander just a bit off heading or height, as the examiner is looking for overall safety, not perfection, and allows for nerves. I found the IMC bit with the foggies to be very brief: as soon as the guy saw that I could turn the aeroplane around he told me to take off the goggs. Bear in mind that, after the diversion, the examiner does the nav back to the field, so the last leg of your route may be academic, but you still have to plan it carefully.
I had been advised to give a full passenger briefing before departure (as I still do nowadays), but the Examiner waved that aside.
Good luck. It's a very intense 2.5 hours or so, but the prize is well worth having.