There is a growing trend to install fire protection sprinkler systems in houses, partly because of the very high level of protection they give. Wales has already incorporate mandatory sprinklered systems into their Building RegulationsThese are the mass of regulations that cover safety, health, welfare, convenience, energy efficiency etc. in the way buildings are constructed. Not to be confused with Planning consent (which is more to do with whether you can put up the building in the first place).
In many cases it will reduce your house insurance. See BAFSA, the trade body for sprinkler system installers and the Copper Development Association do quite a good description of how installations are designed and fitted (in copper, of course!)