I usaully buy one - two year old models/technology.
When a TV is the state of the art it is silly money, but quickly the price drops. And all the money spent buys a lot of beer and DVDs.
A 42" flat screen tv is very chaep now, especially plasma. 42" sounds big, but mounted on the wall it takes up no space and you can sit back and enjoy the TV instead of leaning forward squinting.
I used to have 26" and thought it was big enough for anybody, but I can relax more with the 42".
Plasma give a better picture for low light scenes, so if you like the 'X Files' get plasma.
There is a lot of techie talk about plasma not lasting as long as LCD. For home use the differentce is marginal, both will last longer than most people would normally keep a telly for.
Don't buyt one of the big tellies with an internal projector if you see one. They should be very cheap, but they take upa lot of floor space,a nd it is obsolete technology now other flat screen technologies are so cheap.
I would recomend getting an HD ready TV, I don't know how long it will be before you get much HD TV in UK, but if it is to be in the next 2-3 years, then you will enjoy the benefits.
Don't be afraid to buy korean or Chinese. Both very good at TVs now.