The seed Potatoes are in B&Q and Simpson's and they're not in stock for long, so to make sure you're not left with the dregs I'd buy them now and store them in a cold, frost free place ready for chitting later in the season.
Roosters: Lovely potatoes, never grown them before.
Desiree: Did brilliantly last year so growing again. (Ordered online, not arrived yet).
Pentland Javelin: Never tried these before either, although I did have success with another early last year.
Each bag should do a row, except the pentland javelin, that bag only contains 10 and even if I cut them in half that's not going to be enough for a whole row, just thinking I should have bought two.