My mother took a couple of cruises to the Antacrctic over a decade ago. I've got pictures of her wearing a parka, gloves and a knit cap on the continent itself. I presume that she was layered under that.
One thing I would STRONGLY recommend is sun block, the higher the SPF factor the better. Regardless of the media reports of the ozone layer supposedly healing itself, the excitement isn't quite over yet. The hole is still there and grows in the southern Hemisphere Summer, which is when you are planning to go South. Seven minutes without strong sunblock is enough to do PERMANENT skin damage under the ozone hole.