Seed potatoes should be fine but I never save my own as they do seem to be far more prone to blight and I try to dig out all 'volunteers' ie those which come back up from last years crop. The spores will be lurking in your ground, on old foliage or come floating in. Weather conditions which allow blight to develop are warm and humid nights as well as days - over 10C
There are a few varieties of potatoes which claim to be blight resistant, most notably the Sarpo types. Others include Lady Balfour and I think Cara. There are some more but they are not at my fingertips. I mostly grow the resistant varieties (except Sarpo whioch are quite coarse) but every year I also plant a couple of bags of Mayan Gold which are not resistant but they are so delicious - and we usually get a crop.
If you have bad blight each year then perhaps you should just concentrate on Earlies so they have made their tubers before the blight gets them. They won't store for long but at least you will get a crop.