This is an idea...
Brew an esb or a mild and serve it "British pub style"
If you are going to take a cube and serve cask ale you may want to approach it differently depending on how close to the wedding date you are arriving.
If you are arriving a week or so before you can take it in the cube you conditioned it in but will want to vent it before you fly as a cube will only take about 20-25psi.
You would be best venting it by laying it on its back with the tap uppermost and venting through the tap. Reason being that cubes under pressure sometimes distort the lid and opening and don’t seal perfectly for a few days till everything settles back in place. This wouldn’t normally be a problem if the cube is kept upright but it could be tipped over on the plane and leak.
To vent from the tap you could use a blow off tube from the tap to a glass of water for a couple days and this would be similar to venting a cask with a soft spile.
When you arrive in Perth vent again, through the lid if you want (remove the bung and re fit the tap at this stage, tap should not be on the cube when you fly) and let the cube stand and settle for a few days before serving .
If you have to transport it to the wedding venue ideally you should rack to a second cube leaving the yeast at the bottom of the first. If you don’t need to drive far to the venue you can get away without the second cube but the ale may be a bit cloudy.
If however you are only arriving in Perth a day or two before the wedding you would be best to vent the cube a from the lid (to keep least disturbance to the yeast at the bottom) a couple days before you fly but rack the ale to a fresh cube as close to your flight as you can so you are serving crystal clear ale. It won’t matter that it is exposed to air if it’s going to be consumed in a couple days.
You could cheat and condition the ale in a keg at home then transfer to the cube before you fly just don’t tell any CAMRA members. It wouldn’t even be cheating if you don’t use co2. Just prime and condition in the keg and siphon into the cube before you leave.