Hayley,
I would say that carefully bubble-wrapped and padded with extra scrunched up newspaper in a box would be fine. Doesn't necessarily have to be the one it came in, though. As long as you can fit it into something lengthwise, it should be OK.
Considering it's a reflector, you want to minimise any movement of the mirror. Otherwise, you'll have to spend some time collimating the optics to get the best views.
I hope you have clear skies, because, at the moment, it's pretty shoddy.
Good luck!
H