I do apologise if this thread is a waste of time
Far from it. It's a very sensible plan - I only wish more 18 year olds thought the way you do.
Get a full time job to pay for your flying and build some life experience while you're at it. One thing that many wannabes fail to appreciate is that once you've made it to a right hand seat, flying soon becomes just a job. Admittedly much better than most jobs, and you'll enjoy going to work every morning, but it's still just a way of paying the bills. You will be shocked how quickly this happens - I'm talking months rather than years.
Boredom follows routine, as sure as night follows day. Let's say you move aircraft type and company for a new challenge and more money every three years or so. Let's say that's three years in a turboprop, three years for a low-cost jet carrier, three years for a charter airline. You've now got 5,000hrs or so, and your CV appeals to the big guys. You join EK / VS / BA. If you started in your early twenties, you'll now be in your early thirties - with another 30 years of long-haul flying ahead of you. You will be bored silly, but once at the top of tree there are few places left to go. I got my first job aged 36, so following that logic, I'll be pushing 50 before I have to worry about boredom (by which time I'll probably have much better things to worry about . . .)
Coming back to training, if you pace yourself and work full-time to fund the flying, you'll reduce your debt exposure, have life experience and maturity, hopefully a fall-back career in case you ever lose your medical, and - and this is the bit that gets overlooked - some perspective on working in the real world which you can bring to your flying. You won't spend your entire career knowing nothing except the inside of a flightdeck. You're more likely to appreciate how lucky you really are.