Doubt they need replacing Andy.
However the rears on yours may be pitted due to being an automatic and you not having to use the hand brake as much.
However they could be cleaned up instead of being replaced.
Easiest way to try and get rid of the pitting and clean them up would be to find an empty straight section of road. Get up to about 50mph and floor the brakes. Do that a couple times and that should clean them. If the rears still dont clean then drive along at about 30mph and click up the handbrake a couple clicks for a couple seconds.

Pits will be like tiny rust spots on the face of the dics.
My rears looked like that after the winter salt and not driving fast enough in the bad weather to use the brakes hard enough that the rears would kick in. Cleaned them up using the 50mph method mentioned above. Thought I would have to strip them down but they are fine now.