Thanks for all your posts guys.
Wow colourmesilver, a/c half hanging off would have freaked me out - lucky you could fix it in time!
So later today I had a friend of a friend who is a mechanic come over to see if he could tell what the problem was. He briefly checked under the car and found the diff has a leak, he checked the engine mounts (they're fine) and took it for a drive. When he got back he said it's a suspension problem and said by the sound of things it's more than likely the sway bar links. He's coming round tomorrow with his tools, jack etc to have a better look and properly diagnose the problem (he was on his way out).
I had the sway bar links replaced in another VXII I owned and it cost me $300, I may do it myself this time but if he offers me a good price for the repairs I may take him up on it. The diff leak is minor, but I'll have to tend to that at a later date. Anyway, I gave the mechanic a couple of beers for his trouble, and I'll probably give him a 6 pack as well as $50 for his time tomorrow when he comes back.
I'll post back here with the diagnosis - might help someone else with the same issue. The mechanic said I could still drive the car, so I took it for a spin and noticed it did clunk turning corners, mainly the left side and as well as the intermittent clunking it was doing before. I think I just freaked out yesterday, but it's just one of those things.