QUEENSLAND AQF Certificate III & IV is considered comparable to NVQ level 2 to 3 (GCSE equivalent) The Queensland Certificate of Education (QCE) is considered comparable to the general standard of Level A. The Australian Tertiary Admission Rank (ATAR) is considered comparable to the general standard of Level A. Although both Australia and the Kingdom United are English-speaking countries, there are several differences between school systems that teachers may not be aware of. If you are sure that you will be in Australia for the next few years and he will be able to complete his HSC here, then don't wait for the GCSE.
But after searching the internet a bit, it seems that it is equivalent to the level of GCSE that students in the UK usually do at 16. In short, don't wait for your child to finish the GCSE because it doesn't mean anything here in Australia. This post is directly from an email I received from an SMG reader and was difficult to respond to, since I was from the United States, I had no idea what GCSE was. The GCSE is equivalent but still, what will happen is that your child will finish their 10th year in the UK (I guess they will finish around July), take the GCSE, move to Australia and then start school again in year 10 until December. There would be no advantage if your daughter finished her GCSEs if she is ready to make the move.