UKPassats

Morning fellow passat owners,ive got a strange noise coming from what appears to be o/s/f. Its a sort of clunking/knocking sound(hard to explain)and can be felt slightly through the steering. Ive had all the suspension arms checked but its still there. Its more noticable when pulling away and on bumpy roads but it doesn't do it all the time and i cant hear it when im going faster.
When i hear the noise if i lightly press the brake with my left foot but still moving at the same speed i cant hear it.
Any ideas chaps?
Cheers