For be-seen lights there's a 'TORCH' branded set at Wilkinsons for £8 which are decent 1/2W flashers (from experience they are also rain and hail proof

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For seeing where you are going on unlit roads then the Hope vision 1 is the forum favourite at about £70-75, Planet X have a deal on the Smart Lunar 35 for £15 (I use one of these for most of my commutes in rural Cumbria - but you do have to back off on hills as the light isn't good enough for full attack mode
), and then there are the torch-like lights that range from 1W creee lights at about 80-100 lumen, through to the magicshine/ultrafire style lights from China that claim up to 900 lumen (I don't think my ultrafire torch reaches that, but it does produce a ridiculous amount of floodlighting)