When idling along in 1st/2nd it has a very strong case of kangaroo which is accompanied by clanking sounds from the drive train. If rpm is higher, it'll also do it when rpm output equals vehicles motion. Quite hard to have a smooth drive. When doing your typical 100 point turn in a supermarket carpark

When parked on the hand brake, the rear drive shaft can' t be moved by hand (unless I'm not strong enough), yet if I rock it back and forth via the bumper, it'll roll some 20cm. The rocking motion stops with a clank which seems to come from the rear axle. The drive shaft universal joint (is it called that?) nearest the diff moves slightly each time the clank occurs, but doesn't move during the actually rolling motion.
Haven't got any confidence in the hand brake either. Stop vehicle on an incline, apply hand brake and release the main brakes. It'll roll and rock back/forwards before eventually settling into a stopped position. Could be related to the above?
It's always had the above since I've owned it.
Is this normal?
If not, what are the implications of this and do I need to outright replace the rear axle and more?
Any estimate of the costs involved?
Last passed WOF is dated 22nd Jan 2009, few weeks ago.
Doesn't mean anything to me but might ring a bell with the reader. Recall being told it's got "Rover" axles fitted and something to do with the number "3.5". What are "Rover" axles and what does "3.5" stand for?
Many thanks.