Thanks to everyone for the genuine and helpful replies.
When I say she's been cool with me, she has dodged a couple of requests to meet up over the last few months, saying she was too busy etc. (this was before I told her I was going)
When I texted her to tell her I was leaving, I suggested meeting up before I go. She didn't even acknowledge the request and instead just wished me well.
I'll be having a going away do and I'll invite her.