you basically take the angle between the runway and the wind (so for runway 27, wind of 230 degrees, the difference is 40 degrees). (Lets say the wind speed is 30kts) Then you count backwards from 40 using the 4 i.e. 3....2 - and this reversed gives you 2 over 3 (or two thirds). Then, two thirds of 30 is 20, so the xwind component is 20kts
Think midair trigonometry would be simpler than that!
Hampshire Hog - we've all been there. Sometimes it's just a bad day. I remember it from my interminable Ex12&13 days and was reminded of it recently when I seemed to regress during one session in my night training. Needless to say, all was well in the end.
I remember my first instructor saying that people who turn up expecting to go solo often fly worse. Whether this is subliminal because you're nervous about soloing or that you're putting pressure on yourself to get it perfect so you can and become too tense I don't know. I believe some instructors don't even mention the possibility in case this happens.
Whatever the case, I find that banishing expectations good or bad and concentrating on the job in hand does help with flying (after PPL as well).
Hope next week's weather is better!
