If you have done the NEBOSH Diploma or a degree you should not do the Cert IV as I have been told it is very basic more like the NEBOSH Certificate. If you do not have this then that is another matter. I moved to Sydney a year ago and struggled at first to get a job because of the market at the time and probably because I had no Australian experience, if you register with the right recruitment agencies and make your CV suitable for the Australian market. When I did get interviews they were happy with my UK qualifications and most had heard of NEBOSH. I did a 6 month contractor with a large principal contractor and have now moved to another organisation.