Hi Gruntilda.
I was like you. I had a very good job which I really enjoyed. However, I think it is healthy to change career at least once in your life. I voluntarily jumped ship when the opportunity arose and I started the long road to becoming a pilot. I made it.
The PPL side of things is all very well but it might put you off. It is nothing like flying a modern airliner. Training aircraft, such as Cessna 152 or PA28, are very basic and crude, as is the instrumentation. Flying a modern commercial airliner though is fantastic. Airbus for example have really sorted out the flying experience - it is so satisfying to conduct a flight in an A320/321/330. (I would not relish flying a 737, which have a very cramped cockpit and crude automatics).
You need five things to become an airline pilot: Valid Class 1 medical fitness. Ability to fly. A source of lots of money to pay for your training, (and probably, type rating). Ability to pass all the tests and exams. Getting your first commercial flying job.
The money side to becoming a commercial airline pilot is very significant. You need to seriously research this and ask yourself how much private PPL flying or gliding or aerobatic flying or float plane flying you could do for the money.
If you are going to be bothered by working at odd hours, or getting up at 0300 five days in a row, or being jet lagged, or wanting to have a steady home life, or want to play squash every Tuesday, or bothered by working at weekends and National holidays, or being tired, then airline flying is not for you! You will also have to forego evenings at the pub and parties if you are working the next day.
On long-haul, some people complain about being over the ocean at 0300, but that is part of the job, so what you really need is a positive attitude. When I am there, I look at the stars and the planets, watch the International Space Station going over, do some work, look things up in the manuals, write software, wait for the sunrise.....as well as fly. There is plenty to do if you have the right attitude. Having crossed an ocean at night, the sun comes up and you make a really nice approach and a good landing, which is tremendously satisfying.
As others have said, make sure you have a fall-back position in case it doesn't work out, but good luck !