I like that you respect the friendship you have with this woman, so I'm gonna try and help you out.
First of all, don't stress that it's been 4 years. Sex and foreplay is like riding a bike - you never forget how to do it! The crux is getting started. If she is like 90% of women in this world, she is waiting for you to make the first move. I suggest waiting for a time when you are both relaxed, such as when she is over at your house. If you are a drinker (and you are a fellow New South Welshman so I'm guessing that you are mate), share a couple of glasses of wine or whatever to lower your inhibitions. Start off slowly, maybe put an arm around her shoulder while watching the tele. Holding her hand might sound cheesy but it's worked for me. When things start feeling electric you can lean over for a hug, brushing her cheek with your lips as you pull away. Or you can kiss her hand. In any case, you'll get a reaction from her - it'll either be a green or red light and you can go from there. If she pulls away you can pretend it was just friendly, but my guess is she'll maul you.
Good luck, keep me posted.