A good tradesman will never be short of work, and a plumber is no exception. People will always have water leaks, pipes to fix, boilers to install and service, new houses being built, and lots more. A good plumber is worth his weight in gold, as problems caused by inexperienced workmen can be costly for the homeowner.
In terms of your education, plumbing is seen as a vocational qualification, which means that you are unlikely to be able to study any aspect of it until your formal basic education (GCSEs) are over. However, it will look good for a college or even a company offering an apprenticeship if you can do your best in school and at year 9 choose practical based subjects to prove you are good with your hands.
A good level of basic maths will always stand you in good stead in life, and plumbing is no exception; you may need to measure and calculate lengths of pipe required and possibly calculate the customer’s bill, especially if you get to the stage of running your own business.
For training purposes, an apprenticeship is an excellent place to start, and many companies start advertising just as GCSEs finish, so keep your eye on the local press. During an Apprenticeship, you will be paired with an experienced plumber, and the company will cover the cost of training and help you register with the correct governing body so you gain proper recognition, which is very useful when trying to secure jobs.