I should ad the term HD ready is a bit of a con . All that means there is a socket into which you can plug an HD box. As you probably know HD boxes are far more expensive that the normal Digi Boxes and there is a very limited amount of HD broadcasts available.
If you go into Comet they have a booklet that sets out the options . My friend recently had a Sky box and dish fitted for a one off payment of about £40.
Sky hope you will then sign up for one of their opional packages, but he didn't . Neither did I . The Freesat box and dish was more expensive.
Several flats with balconies near me have their dishes just standing on their balconies. You have to be facing east for that to be suitable.