I have a similar noise - can I check your symptoms to see if its likely to be the same thing please?
On a good road there is no rattle / thud but if I go down a badly paved road (my local town roads for instance) I get a constant knocking noise - sounds like metal on metal clunk. It drives well with no noticeable pulling, diving or handling issues. Local Skoda garage (Motorline Medway - previously Sherlodge) had it for a day and could replicate the noise but couldn't identify it. The noise is offside front but I can't narrow it down further than that.
My car is a 2012 Superb 2.0TDI 4x4.
Any help so I can look myself or have the garage look again would be appreciated.
One last thing - about 100 miles before the noise started the garage replaced the water pump / timing belt and front pads and discs so I am not ruling out something not going back properly after that, but as I said they had it back in for a day and couldnt find / rectify the fault.
Thanks, Neil.