Take the plumbing career into consideration but have back up plans as well.
I have in region of 50 odd hours flying and ideally a commercial pilot is my dream job but there are many ways to get there.
Loans
Write to airline companies asking for work experience, and who knows they may take an interest in you (there is no harm in trying)
Military
Most people work a none aviation related career and decide later on to do there ATPL training. As for myself, a military career seems to be going well and would love to get in, however I am considering using my A level grades to help land a job as an estate agent. I believe I have got the right characteristics for that job and it will certainly make getting on the property ladder a lot easier with the input of parents.
Try getting some flying lessons in while finishing your last year of school, from that you can finalise your future career plans.