Scoop, I came over in the first intake in march so can only tell you what I experienced but I don't think it's changed much. When you get here your at PTS for 4 weeks covering first aid, EWP training, familiarisation training, site induction and all the other certificates you need to be able to work on site and on the network. While you are at PTS you will have an interview with a cert three assessor. There are a load of skills you need to be given a cert 3 and he will go through any certificates or proof of experience you may have brought over with you. He will also ask questions just to check you know your stuff and not bluffing. He will then tick off some of the skills you have proven you have and that are also recognised in Australia. After this is done there will be a list of courses you need at attend to complete your gap training. On some courses you need to show evidence that you are competent even after completing the course so you need to submit evidence packs showing what you have done. It's not too difficult and once you get your head around the system it all appears straight forward. There are some courses you just have to do even though you are qualified in the UK as the qualification isn't recognised over here so you need to get the Australian equivalent. Everyone is in the same boat with this one so you will find all of the intake need to do it whatever their background. Getting the cert three will take about 12-18 months we have been told.
What I will say though is take every certificate and qualification with you no matter how insignificant it seems in the UK as you never know it may be recognised over here and save you some additional training.
Margaret River is a lovely place..
All the best..