Couldn't find any info on what scale this was done. Is it actually 1:1?
If so, interesting achievement, I guess. But it would probably suck as a Minecraft world. The UK is a beautiful country, but in Minecraft terms it would be almost entirely one base biome, and not a very dramatic one at that. Cornish coast or Scottish highlands are probably where I'd base myself.
What this kind of detailed geology really calls for is Dwarf Fortress.