I was supposed to be meeting up with this girl I'm seeing today, we were supposed to meet up at 12:30, I was just getting ready, I live a few minutes away from where we were meeting and I got a text saying shes still over her friends house and would text me when shes on her way down.

I was a little bit pissed off, but I said "Okay, that's cool" an hour later, I'd still not heard anything so I decided to cancel because I'm not going to wait around for HER to decide when she can be bothered to leave her friends and come and meet me.

From reading this forum in recent months, I assume that was the best thing to do?

Well lo and behold, I cancelled and said I was going out, and SHE said

"Oh, okay. I'll come back to yours after, where are you going?"

You shouldn't have waited for her even 15 min let alone an hour. Cancel it, call her out. "I gave you a chance and you blew it, you had no respect for my time"
Unless she puts A LOT of effort apologizing to you, otherwise just ditch her.
Dont tolerate her bullshit.

i agree with taohackne.