After a bit of research I decided to go for the Manfrotto 676B as Thomas had. I must say that I am very impressed with it for just £30 pounds. It feels really sturdy. It doesn't look cheap and nasty. In fact it is pretty pleasing on the eye. It seems to perfectly compliment my D40 with the 70-300mm lense.
I am going to take this with me to a motor racing event next weekend at Donnington Park. It should take some of the burden off my neck and shoulders while also lending me good stability for taking shots. Also importantly it should minimise fatigue over the course of what will be a long day at the track.
Another thing that I am really impressed with is that fact it weighs so little at around 400 grams and is so compact to boot. The only gripe I have is that the strap is a little bit slippery in that it doesn't grip the plastic clip. This sounds like the same problem that Thomas described. All in all however my first impressions of the Manfrotto 676B monopod is that it is a near faultless product that perfectly suits my needs. All I need to find out now is how it handles in the field or in my case at the track.