Def sounds like a front suspension Bush! especially if it happens when u apply lock. the actual components only cost me £30 when i replaced mine. But they where a pig to replace on my (much easier on other cars) i found the easiest way was to be rough with them!!!
Dunno now! lol could be loads of things. i know it sounds stupid but have u checked your spare tyre is in correctly? i had a knocking for ages drove me mad but that's all it was! if i was you i would go 2 a garage and have a diagnosis only because u could spend 'x ammount' on a part and it could be sommat completly different!! just 1 of them things when there is a knocking!
well i have to carry load of gear in my boot, mainly for work and stuff. im going away next weekend so ill remove everything and see if the noise still occurs... other than that i cant think of nothing else...