If you have a Router at home and intend to use it mainly at home then go for the Wi-Fi version - as mentioned at £109
Kindle (Wi-Fi) is a great choice if you already have a high-speed internet connection and wireless router setup at home, and do not want the added convenience of a 3G connection which enables you to download ebooks anytime, anywhere on the go. If you do not have Wi-Fi setup in your home, Kindle 3G would be a better option.
Kindle 3G (Free 3G + Wi-Fi) is the easiest option because there is no wireless setup—you are ready to shop, purchase, and read right out of the box. Built-in Free 3G connectivity uses the same wireless signals that cell phones use, but there are no monthly fees or commitments—Amazon pays for Kindle’s 3G wireless connectivity. The added convenience of 3G enables you to download ebooks anytime, anywhere on the go—without having to find a Wi-Fi hotspot connection. With wireless coverage in over 100 countries and territories, Kindle 3G is a great option for travelers. Check 3G coverage area.