Terrestrial HD services (through Freeview) are in their infancy and there are currently only a few TV sets with a built-in Freeview HD tuner. If you specifically want such a set you can see the range by going here:
http://www.freeview.co.uk/freeview/HD/Products
Click on 'I want a new TV with Freeview HD built-in'.
(Note that the results shown will only be the first of 5 pages. Click through the 'next' links to see the full range).
The TV you're considering purchasing has an 'ordinary' (non-HD) Freeview tuner built into it. So you'll be able to watch Freeview channels but not in HD. However the set is also 'HD ready', which means that it can accept and display a signal from an external HD source, such as a Blu-Ray player or a separate Freeview HD box. (There is currently only a small range available. Click on 'I want a Freeview HD box . . .', in my link above, to see them).
Chris