Upgrading to LEDs will be an expensive process that will set you back £1000+. It will need to be professionally fitted and will probably require considerable upgrades to the wiring and electrics to support the LED system. Do not buy a set online and fit them yourself - they could blind other drivers or melt the wiring and pose a fire risk.

Aftermarket high-intensity discharge lamps (HID) are now banned (and result in an instant MoT failure), which means your only affordable option is to try another brand of halogen unit. Personally, I don't think there is much difference in light quality, between the various halogen bulbs on sale, but your local mechanic might have a set that will address your poor dipped headlight quality.