Ok, not 100% sure if this is brakes/suspension but firstly it feels like I have a sticking rear caliper. I had new calipers fitted around July last year, would these seize already?

Or is it rear suspension related? Symptoms are: come to a stop and the rear driver's side feels like the handbrake has been left on, so the car rocks a bit if that makes sense? I do have a fully re-built rear beam and avo adjustable dampers ready to swap over but have been thwarted by rusted disc protector bolts!