Lazyb - I probably wasn't being very clear. Just after the car comes to a halt, there's a sort of clunk and the car tries to move forward. It's as though the drive WAS disconnected when slowing down,then re-engages as soon as the car reaches a standstill. I'm so used to the Focus box (we have an 03 plate Focus Estate Auto as well) which is smooth as silk, this seems strange - but I think it is a different model of box, so that could account for it.
Richard G - good idea - I'll have a look/phone around and see if I can locate a similar model for a trial drive.
Thanks, both - much appreciated.