Wow, that sounds like fun! I much prefer real rollercoasters to the one we have been on! I hope you have lots of fun and great weather (should be the best time of year!).
Flying is a high risk activity for lymphedema but if you only had a sentinel node removed, you should be fine. The clinic where I went for treatment last month provided the following guidelines for me - I am to wear my compression sleeve while flying and for 2 hours afterwards. Apparently this is to do with how the different pressure affects the lymph system. But I had 8 nodes removed and have had trouble with fluid build-up. If you are not at high risk then you may be fine to just fly and enjoy yourself.
If you have someone like a physio that you have seen for your cording you could check about whether they think you should do anything as a precaution. Good luck with your upcoming mammo and hope you and your family have a fabulous time on the Gold Coast! Deanne xxx