Being a web designer and particuularly having worked in UK websites for several years I saw some speacial features in uk websites which I am going to share here. And what I am going to share is not any rule but just what I experienced so far.
UK Web Designing and red color : If you are designig a uk based websites, we recommend you not to use red colro as message. Red color means angry color. Rather than usign red color you can use maroon or other color.
Uk Based e-commerce websites : If you are developer you are recommeded to use buy now button jus beside product sot that customers do not have to grope for buying your product.
Whenever you show error message , you should use please word every time. I have seen Uk people like please keyword very much. Though every civilized person likes this word but they like it more.