Knocking drive shaft? Or worse?

I've got quite a loud clatter when accelerating with any steering lock on, worse on right turns. Seems to be some play in the LH CV, but it sailed though the MOT and the MOT mechanic said it didn't seem too bad to him (and that diesel automatics always sound like they are broken). I've also had rattling CVs on Audis before (swapping left to right was a cheap way of getting 10's of thousands more miles out of those), but they've never sounded this bad. Is this typical on these cars or could it be something else? It's a 1.9PD with DSG. Do diffs go? What does that sound like? I can't think of anything else, but the car does also have a weird handling problem - it feels like it sways from side to side at speed on the motorway. Nothing coming back through steering wheel and it tracks straight, but something isn't as it should be.

If it is the CV, are cheap pattern drive shafts any good? I've found a company in Birmingham that sell drive shafts with a two year warranty for £50 on Ebay (as do Eurocarparts though I'm not sure if theirs are DSG ones),