Harry Rowland. He'll see you right.
He's one of the best wheel builders in the UK. He can have a short waiting list but if you give him a ring he'll chat about what you need and you can order straight away.
An alternative could be Hope RS-Mono Pro3s. Hand finished by Hope (tensioned, etc) they are Hopes MTB derived hubs on Open pros with 32 ACI spokes. 105s are good hubs but for coping with UK weather I'd go with the Hopes. Be aware that the Hope hubs buzz quite loudly though.
As for the Magicshine you've got, just make sure you keep pointing it at the ground. So many 'tards ride round Richmond Park blinding everyone in their path with those things. Having got sick of replacing my lights every year I've invested in an Exposure Flash / Flare combination. Very bright, very small and very good. So far I'm impressed.