It's a rather pedantic point but, without a subscription, a Sky box becomes a generic FTA (= 'free to air') satellite receiver, not a true Freesat one. You'll be able to receive all of these channels:
http://en.wikipedia.org/wiki/List_of_free-to-air_channels_at_28%C2%B0E
A proper Freesat box is actually configured to receive a subset of those channels plus the Freesat EPG (= 'electronic programme guide') and some 'red button' channels. To get Sky's EPG (plus some interactive facilities) you could also purchase a 'Freesat from Sky' card, for £25 direct from Sky. (Confusingly, 'Freesat' and 'Freesat from Sky' are two different services).
Whether it's generic FTA, Freesat or Freesat from Sky, you'll get most of the terrestrial Freeview channels (plus quite a lot more) but it's worth noting that you won't get the free UKTV channels (such as Dave, Yesterday and Drama), which happen to be among my own favourites!
Once your Sky subscription ceases your Sky+ box will no longer record programmes. Further, any programmes that you've already recorded will no longer be available to watch.