Lumicycle has been making quality affordable lights in the UK for what seems like an age.
Although it hasn't jumped on the LED bandwagon big time (though it does have an LED unit), there is still a lot to be said for its traditional over-volted halogen lights. Our system consisted of the Pro 4.4Ah battery and a single lamp unit with a 12-watt, eight degree spot bulb and a halogen glow ring on the front for excellent visibility (it's only £3.99, well worth it).
The clamp is similar to Blackburn in the fiddle stakes and the battery we chose was of the water bottle style - when it's cold and dark we tend to use a hydration pack to keep our drinks a little warmer. It gave off a nice warm light (good for contrast) that was bright enough to ride with and yet offered truly excellent visibility thanks to the addition of the glow ring.