According to Clove, the Radar and the Sensation XE should be in stock starting October 4, while the Titan is expected to arrive three days later, on October 7.
The HTC Titan (a true Windows Phone Mango flagship) will be the most expensive handset among these three, since it's priced at £498 (including VAT). The Android Gingerbread-based Sensation XE will cost £492, while the Radar (a mid-end Mango phone) is going to cost £342.
Apart from being available unlocked, the Titan, Radar and Sensation XE will also be sold via various British networks. For example, O2 will offer the Sensation XE, and Orange is going to sell the Radar.