Peugeot 308 Space wagon 1.6HDI, screeching noise from alternator area? 2010 model.?

This is very typical of a loose drive belt, probably to the alternator. It is not harmful if the warning light is not on, just annoying.

There is an adjustment which will have to be tightened until you can push the belt down about 1 cm on its longest run.

Also while doing this closeley inspect the belt for cracks, fraying, or delaminations, which will mean replacement.