I don't know - I joined the Dukes because I couldn't do maths!
One would presume that if you earn the dosh overseas and leave it there you'll not get taxed - butI would say it would have to be declared. OK, my wife does the taxes in my house - but there's a few blokes who I now work with over here who are ex UK Forces. One declares it & is therefore taxed by Aus and the other is doing the dodgy. Up to you. I was a 5 year Offr, so was still red a red arse. Oh, wait, I will get about 1200 quid a year when I'm 65.
I do know how many points you get for a try though.