To be serious. In the absence of witnesses it's a hard task to show careless or dangerous driving, Gary Mason was killed 12 months ago when a WVM knocked him off his bike early in the morning - the case against the driver was dropped in October due to no witnesses. The Highway code recommends the wearing of high vis, lights and a helmet, the lighting regs require lights and reflectors at night. Whilst the highway code is not law it can be offered as persuasive evidence, lighting regs are law. Best stance to adopt is leave as little doubt as possible by adhereing to the guidelines and law - it can only help your case.
Headlamps reach about 40 ft infront of the car on dip. If you're doing 40mph and a cycle is doing 10mph you close at 30mph (43 feet per second), that gives you less than 1 second to react, it takes 0.2 seconds for the brain the send the message to the limbs and then more time to apply the brakes/steer.
A well lit bike can be seen from over 200ft away.