Smart keeping the invention to yourself. However, the only way the U.K. government would be in the least bit interested was if it somehow brought them world peace without unnecessary bloodshed. And remember if your invention is extremely interesting and your manage to pique the interest of the government, it may be leaked to other sources with far different agendas. Keep it well hidden from few beyond your family and friends if you treasure your invention. Also, mold your amazing invention into something feasible and rational; if you cannot, then make sure to clearly define its end benefits for the world. Depending on the type of government organization-national security, political, or economy-you might need to visit their website immediately and find contact information. From there, ask your parents to help you-the government might not listen to a kid without an adult present.