My most embarassing moment was years ago now but the shame still lives with me... my mare and I were hacking through a farm yard, there was a new beautiful totally jet black TB type boy there who had been put into a make-shift paddock right by the track. My mare always had a thing for those...
Sun a-rise by Rolf Harris (don't judge me!) if I want her to walk rather than bounce
"What's that coming over the hill is it a monster, is it a Monstaaaar" etc
am now going to learn Pinkwellies song, that is fantastic!!
I was scared on my youngster quite a lot, someone told me to ride with a neck strap - an old stirrup leather does the job nicely - so that you have something else to grab onto if they do go up / spin round and it worked wonders, just gives you that bit of added security and stops you jabbing at...
this place is just on the edge of the Epsom Downs, you need to hire one of their instructors or bring your own but might be worth a look:
http://www.wildwoodsriding.co.uk/ownHorse.asp
I'd go with the rescue remedy as well, and also give some to the horse - it really does work and makes them a little less likely to react badly if you do start getting worried, and remember that every one else might look confident but virtually nobody actually is!