By God Emma you are always a Plan A+++
I never have a plan B, nor do I want one, I plan my encounters far in advance and know what I want...if it goes sideways (only happened once...for a good reason) I will wait for my next chance. If I really want to see X person (which is why I chose them) how could I have as pleasurable a time with another that just happens to be available. My expectation was for X and Y may not offer the same things or be the same body/look type.
I dunno, I guess I have never felt that I have to have sex today or right now no matter what...I prefer the experience over the simple act. Currently I have 2 encounters set up this month (hopefully a third soon)and eagerly anticipate each one...if they fall through at the last minute, I will be disapointed, but will just go home and watch some porn methinks.
As to what you do, it is a bummer, but put the planned money aside and move on, the best thing about hobbying in Ottawa is the sheer amount of amazing women we can encounter. I would still send an e-mail and give her a chance to let you know what happened, if it was an act of God or explainable reason I am sure she will make it up to you. If not visit the announcements section, then the recommendations section and try to contact another lovely and interesting woman for an encounter at a later time.
I think especially because you are new at this you should make sure you do all you can to ensure you will enjoy yourself, pick someone that suits your fantasy and not just your immediate urge...if you do and it's mechanical or not what you were looking for, you may not want to try again as you were double burned.