[color=#000000][font=verdana, geneva, lucida,]I have a knock coming from the rear of the car on the passenger side, its more obvious when going over a bump and i have noticed that the tyre is worn more on the outside edge than the inner. I have taken a look and it doesn't look like anything is broken so i think it might be one of the linkages or bushes.[/font][/color]
[color=#000000][font=verdana, geneva, lucida,]Whats the best place to start?[/font][/color]

Rear bushes or suspension top mount, I had a similiar knock and it was the exhaust pipe, but no tyre wear

try taking it to get a rear tracking done as they are adjustable on the back...be aware of seized tracking bolts that go through the link arms and subframe i had to change the subframe on mine

Is there anyway to check what part it is?

i used pro tyre they done mine 4 me with no problems and after a gd 2nd hand subframe and track for 30quid was happy