Carpet Newbie - recommendations, tips etc please?

Arfa__

Just about to get our hallway decorated and part of the plan is to get carpet up the stairs. Its one flight, with couple of bends, one with diagonal steps the other with a small square landing (approx 1m^2) with a further two steps coming off at right angle. The adjacent floors top and bottom have varnished floorboards. Carpet would have to go full width of stairs, too much hassle sanding, preparing wood on stairs. Stairs are just exposed wood currently.

I've never brought carpet before, never paid a lot of attention to carpet to be honest. Not sure what I should be after and what's best. My intention is simply to get the hallway finished and presentable ready to sell the house.

So my questions:-

• Any company recommendations in East London/Essex border area? Conversely is there anyone I should avoid (bad service/over priced etc)?
• What sort of rough ball park price should I expect? Hours of labour etc?
• Is there a particular type, grade or thickness of carpet/underlay that would be best suited to this application (and reasonably priced)?
• Bearing in mind the house will be going on the market soon and that the walls will be magnolia and wood is an antique pine varnish, what colour/style carpet would you recommend?