http://www.findmeglutenfree.com/sear...W,%20Australia
The Find Me GF app works worldwide.
The Schar GlutenFreeRoads website is international as well:
http://www.glutenfreeroads.com/en/
Make sure you take the restaurant cards with you that explain what you can/can't have, and why you need it gluten-free:
http://www.celiactravel.com/cards/english/
Also it appears that Australia might be even more GF friendly than England (if you can take one traveler's word for it) and I found England to be a GF mecca compared to the fried-food capital of the South US that I live in.
http://www.celiactravel.com/stories/...-in-australia/
For me, I would take enough granola bars etc for the trip, because airline food sucks for GF usually, but hit a supermarket first thing and stock up on bars, dried fruit and nuts. Just because they don't have your brand, doesn't mean that they're not safe (after all, Celiacs live in Australia, too) and delicious.