You can get a Plumbing Apprenticeship if you are over the age of 16 and live in England. You cannot be in full time education but you can apply whilst you are at high school. To get a plumbing apprenticeship you can use the governments website to see what is available. You can also contact colleges and companies in your local area to see if any are taking on apprentices.
If you get a plumbing apprenticeship you will earn a wage and get holiday pay whilst learning the trade on the job with experienced plumbers.