Links

http://www.pponline.co.uk/
Contains a lot of articles relating to sport and exercise, including methods of training, nutrition, injuries and supplements, as well as many other topics.

http://www.netdoctor.co.uk/health_advice/facts/loseweight.htm 
A very good article on the facts of weight loss, includes BMI (body mass index).

The British Nutrition Foundation
An excellent website on nutrition.