I think it very unlikely you are going to be able to store the harvested potatoes well enough to be able to use them for the whole year. That said you would need to grow a main crop potato, lift in tubers in September time, leave on the surface to dry out for 24 hours (so make sure it isn't going to rain), brush off all the loose soil, bag in hessian (not plastic) sacks and store somewhere cool and dry. You'd need to check the stored potatoes on a regular basis and remove any that were starting to rot.

If I remember correctly another member does have good success but you do need good storage facilities.

Our veg man keeps his all winter successfully like that. The old way used to be to make a clamp - this is a heap insulated with straw. If you put Potato Clamp into Google you'll find several lots of instructions. I don't know how you prevent the heap heating up though.

Thanks for your input. I do store my pots in hessian sacks and will most likely continue to do so. I think next time around I will buy a combination of earlies and main crop.

The earlies certainly taste nicer too.