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). See more on the regulations .
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!)
The Building Regulations cover fire in part BThe Approved documentsApproved documents (England) are detailed publications which come under the English Building Regulations. They are based on tried and tested methods of building and if you follow them you are assured of complying with the Regs. The equivalents for Scotland are the Technical HandbookUnder the Scottish Building Regulations, the Technical Handbook gives construction principles, which, if you follow them guarantee compliance with the Regulations, for Wales: the Approved documents (Wales), and for N.I. the Technical BookletsUnder the Northern Ireland Building Regulations, the Technical Booklets give construction principles, which, if you follow them guarantee compliance with the Regulations, (England) part B, deals with fire of the Approved documents (England)