Firt at all, Spanish is the second most spoken language around the world and the most use in business, it is a fact.
Secondly most of the primaries and secondaries schools have Spanish in their curriculum and children study at least tow hours per week.
Thirdly traveling to South and Central America has increace in last years and what a better enjoyment when you can communicate with people on their language.
Spanish is an option for GCSE and A Lavel, do not wait until your children have to take them. Let them start from an early age when they will learn the language without an accent