IAM Test
I think they will do it no matter what - if the examiner is happy to go out then so must you. Mine was on a day with wind speed of +30 and gusts on top of that - bike was like a sail board on the Derbyshire Dales. Passed and was told I could have done a bit better with positioning - yeah on a less windy day.
As for wet weather riding, I think that I'm cautious, but an observer thought I was confident, especially after he nearly dropped his bike following me. So I guess you never know. If you follow the plan of info, position, speed, gear, acceleration then you won't go far wrong. It always seems easy in principle but think about your last run, had you finished all your braking and engaged the right gear and throttle before tipping into each corner - I'm still trying. General principle, brake earlier, brake harder, cornering easier, accelerate earlier.
Still got 5mm to scrub on the sides of my Avons, and yes they seem unsteady in the wet.