Kestrel is definitely one to try, it is the mainstay of my potato crop. I leave it in the ground just digging a few roots when needed, some years well into November with very little slug damage.
I usually grow a couple of rows of Maris Peer each year,and lift them quite early for 'new potatoes'. This year I did notice more slug damage than usual on them especially the last few roots, so I wouldn't rate them as slug resistant.