In analogue days the edges of the TV picture were ill-defined, so TVs deliberately cut off the edges to keep a clean picture. Your TV is one of these. Unfortunately Sky don't make allowance for this and put the text right up to the edge of the picture.
Check the TV's menus to see if there is an overscan or picture width setting.
Lots more on this here
http://en.wikipedia.org/wiki/Overscan