Ok ive noticed that the left front caliper is loose compared to the other 3. So my conclusion is that there must be either a pad spring missing or a shim. Would this make the caliper moveable ever so slightly (enough to rattle and **** me off)?

 

open up your calipers and look for yourself. there aren't any springs, and no shims on aftermarket pads (maybe not even stock, can't remember).

how is the caliper loose? maybe pads have to be replaced, maybe caliper is sticking, maybe you have more work to do.