I would suggest Miche X-Press fixed/free hubs, but AFAIK the 36h version isn't imported to the UK.
In terms of rim, Sheldon reckoned that a 700x32 tyre might just fit on an Open Pro, but to be on the safe side you could go for an Open Sport. That would make £45 for the rims, about £65 for the hubs and maybe £25-30 for the build+spokes. Total= £140 max.