You'll most likely find that you'll have 32", 37" and 40" to choose from with LCD/LED tvs these days, so I assume you'd be looking at a 37" tv?
In which case the 37" 1080p LED LG tv from Richer Sounds at £399 is a good deal, especially at that price range.
LG 37LS5600 | 37 inch LED TV 1080p HD Ready Freeview | Richer Sounds
You say there are lots to choose from - what models are on your shortlist? The LG is probably the best value for money - there aren't actually many branded 37s under £400...37 is quite a rare size, you'd have more choice in a 40"
Yes, can get something decent. Oddly, due to supply and demands, 40s are about the same money as a 37"
This one is 3D and a few quid over £400
Samsung UE40EH6030 | 40 inch 3D LED TV 1080p HD Ready Freeview HD | Richer Sounds