What Carl has said is correct, and I would take that option, but if it was a large company which wanted copyright, personally I would go through the Trade Marks Bureau, which costs £70 per annum.
The option for small websites:
http://www.copyrightservice.co.uk/co..._copyright_law
The option I would take for a large company:
http://www.trademarksbureau.co.uk/copyright.html
If your website is just a personal website, I wouldn't bother paying £70 per annum, I would stick with the free copyright. The 'free' option isn't the cheap way out of it, every member in the UK is covered as soon as they make their product, but with the Trade Marks Bureau, you are garuntee'd you are covered as they will do extensive research, unlike the 'free' option.
I hoped this helped, kind regards,
Craig Embleton.