Hello there,
I do Chemistry, Physics and Biology (as well as Enviromental science, further and english) (currently in yr12). I find physics easier than biology, but I've got a great physics teacher. There are mostly formulas that you just plug the data into to get your answer - much easier than trying to remember all of the nuts and bolts of biology. Biology is a lot easier if done with chemistry, because a lot of the concepts of chemistry (that are glossed over in bio) are really useful when looking at the molecular structure of cells. Like, REALLY useful. Half of biology, at least at the yr12 level, is chemistry. And some of chemistry is biology. There's quite a large crossover.
With physics, although there are crossovers from chemistry too, they are more just "oh that's why that's like that", rather than "thank God I took chem, otherwise I wouldn't know wtf is with all these lipids and proteins"'
So, for that reason, I'd take physics first, because then when you take biology, you might have a greater knowledge of chemistry that will help you learn the concepts