@Ictyes an HDMI cable is about £5 and freeview has now gone HD so BBC would be availible for a one off fee for the correct box.
I remember reading somewhere that FOM were recording this year in HD but not broadcasting it. I think it may be lies as you can tell when its been downsampled from an HD signal to SD.
Finally as for HD being worth it or not, 1080p is actually better than the eye can see at 25 fps they needed to up the real frame rate to make that worth it. But it still is a definite improvement, especially over NTSC in america or any analogue broadcast. (I’ve just finished a degree with all this stuff in)