pulse1 - maybe Lands End should use Arial font instead of Times New Roman....
My worst moment to date also involved using the wrong runway. Before leaving for an unlicensed airfield I tried calling for PPR and to check weather, runway in use etc. but I couldn't get an answer. My flight-guide suggested that the A/G service was often unmanned so getting no answer was no great surprise.
Approaching the airfield I made the usual radio calls for traffic and joining info. This call was unanswered so again I assumed the A/G service was unmanned. I could see no other traffic in the circuit and so flew overhead to check the windsock. It appeared to favour a certain runway but there was relatively little wind.
Messing up the approach completely I opted to go around, only to find another aircraft rapidly breaking off his base leg for the conflicting runway, having seen me climb out after the go-around.
As I passed 500ft I heard a radio call to "the aircraft that has just departed easterly - you're on the old frequency. Please change to....."
Turned out that my flight guide had the old frequency, even though it was fairly new, and because I couldn't get through on the 'phone I had no opportunity to check that I had the correct one. This particular airfield has a preferred runway, to be used unless it results in a tailwind of quite a few knots. So consequently I turned up unannounced, on the wrong frequency and using the wrong runway!
After a cup of strong coffee and many apologies, I made my way home like a dog with its tail between its legs, vowing to do better pre-flight planning in the future. I beat myself up over that one for quite a while, but now just put it down to experience. To err is human, they say...
Oh, and I've also pulled the mixture to ICO in the circuit, but thankfully realised within half a second as the revs began to drop. The instructor didn't bat an eyelid, so either I was so quick he didn't notice, or more likely he thought "what a plonker" and has seen it all before....