Thunking / knocking noise coming from rear when going over bumps

[thefunkygibbon]

Without taking it to a garage and crying gently to myself because of costs,

will try to get a video of it. but its def not engine related. can hear it only at slow speeds.
does anyone know what it possibly could be and if it is at all possible to diagnose myself by getting under the car and moving things around? ? i've just bought myself some car ramps.
i have been told it could be the trailing arm, or the ARB... but could be a couple of other things.

sorry, i'm a bit of a n00b when it comes to cars to be honest. but i'm ready and willing to learn... obviously if its a hard part to replace i'll get it done by a proper mechanic if it needs to be done urgently.