You'd want to make sure that your school considers it to be an approved absence (in most cases, it won't be) and ensure that you don't infringe on any absence policies in place (e.g. min 90% attendance). I personally would not endorse taking a week off for work experience if you're in Year 12.... even if you're in another year other than 12, missing any sort of school isn't great because the content, discussions etc. that you miss out on could be important. The compulsory work experience during Year 10 is OK because the programs are cancelled during that week so you aren't missing out on anything. Try to schedule work experience and other activities outside of school hours if you can.
If you're an independent learner and your parents are OK with it (and you aren't in Year 12 where attendance is super important), then i'd say fair enough but make sure you let your teachers know at least a week before hand so you can get the work needed to catch up before you return. There's nothing worse as a teacher than a student who goes away / is absent for a lengthy period of time and returns with the expectation of the teacher catching them up 1 on 1 while the rest of the class has to wait and lag behind.
With work experience in general (and even when you go for jobs), you can't be too picky. Just getting something in general that is somewhat relevant is more than some people get.