Welcome to MBc, lessells, Now that you have introduced yourself, be sure to read all you can, including the 'Stickies' at the top of every Forum. They contain a lot of information. For example, ‘Sticky’ by Al.Fisherman has 20 or so links to “How To…” threads, and important pages for you to follow. ‘Sticky’ by Anton "Forum Rules and Infractions” is a must read about how you are expected to Conduct yourself. However, read all of them, and be sure to use the search feature. Almost every question you might have has already been asked and answered someplace here.
I really don't know how paint stores work in Perth, but in the U.S.A., you can take any paint chip, painted piece of metal, actually any paint sample into your favorite local Paint or Home Improvement store. They can put it in a spectrophotometer (which will undoubtedly have some spiffy, proprietary, name like: 'Magic Color Matcher', 'Automatic Colour Hue and Try', 'Colour Matcher and Mixer,' or some such nonsense) and match the color. It is, however, a real machine and really works. I can't give you the exact technology involved, but I know they can do it in a matter of seconds and don't charge you for it. Then they'll mix the paint for you. Check it out, and good luck to you.
Patrick