I put 'chunky chips' into WW Plan manager and the average is 7PP per 120g portion. These are for oven chips so 10PP sounds fair for a small portion, if you knew the cafe fried them however I would point higher.
tbh id go with the chippy chip values 210g = 14pp and 410g = 26pp (210g = cone, 410g = small bag) as with the cafe ones they cook em in a lot of nasty oil