I was advised to add all the ingredients together to get the full number per loaf and then divide it by how many slices I can cut it into - its not totally accurate but is the best I can get to working it out. In my case on gluten free bread it worked out at 5 points per slice from memory so I gave up and went back to cripsbreads for a while!!!
I try not to eat much bread personally, but I'd treat it the same as a fresh-baked farmhouse loaf from the supermarket...which is about 2 or 3pp for a 35g slice. Not sure if that's right, but I don't imagine there'd be much difference between a home loaf and a shop loaf.