In reply to sbc_10:
I did this on winter attempt couple of years back.
Rang the first hut on morning we left and then booked the subsequent huts the night before. Using warden or there phone if no mobile reception.
Pros, little planning needed and no cancelling of huts required if bad weather etc.
Cons, may be no space booking this late, the guardians may try and swindle you for food even if you don't want it and are not obliged to pay!
Do always try and book though, as helps out guardians and saves them being annoyed.