Wow! An Apple Time Capsule with 500GB hard drive for £99.99 including VAT and delivery! The Time Capsule is an Apple router which will create an 802.11b, 802.11g and/or 802.11n wireless network. It contains a 500GB hard drive which is ideal to backup a laptop because the drive can be seen on your wireless network. The router also has a USB socket which can be used to connect another hard drive or a printer or even a USB hub to which you might attach several devices.
Be aware that this is a router and will not by itself connect to an ADSL broadband provider. It needs to be connected to an ADSL router or modem, or a cable modem.
This price is an absolute bargain - the current 500GB model is £229. It is an older model, but lacks only a couple of extra features such as allowing you to run two separate wireless networks (g and n, for example), but if you are connecting it to an ADSL router, your current router can do the g network and the Time Capsule can do the n network, so the end result is effectively the same.