1998 polo rear suspension unhealthy. help

hi there, i have ( well my missus has) a 98 polo 1.6 cl auto, I've noticed when going over uneven roads the rear end feels like its skipping all over the road, it remibds me of an old escort i had when its bottom ball joints on the front were worn, but the polo its happening from the rear.....I've got the car to teach the useless cow to drive in (she is useless in a manual lol) ....I've not had a look under the car yet but shall have a look soon....just wandering if there is any common faults that cause this on these. I'm a tool and plant engineer so the physical side of repairing it is not an issue, just need to sort it before i get her behind the wheel.

thanks in advance

tom