HDTV is still in its infancy with terrestrial TV (i.e. on Freeview). Normal Freeview services don't have the bandwidth to carry HDTV so you've got to wait until the transmitters in your area are ready to broadcast in HD. (When they do, you'll need a special Freeview set top box - see the link below). In my area, HD won't be available until next year, and then only on the sole BBC HD channel, together with ITV1 and Channel 4. (It's worth noting that programmes have to be made in HD. Even if all of the other channels were able to broadcast in HD you wouldn't get HD reception unless they transmitted programmes made specially for that format. So there's no point in any of the digital channels which only show old repeats bothering with HD)
http://www.freeview.co.uk/freeview/HD
To get a wider (but still limited) range of HD channels you have no choice other than to subscribe to Sky
http://www.sky.com/sh...telly/home/index.html
or, if your area has the cabling, to Virgin Media:
http://allyours.virgi...com/html/tv/hdtv.html
As Lslowry indicates, Blu-ray disc players give their best picture when used with an HD-ready TV.
Chris