I was where you are about 2 yrs ago
Speedbird,
I was in a similar position to you - well paid but ultimately boring office job, have wanted to be a pilot since aged 4. Resigned from office job aged 33 in Sept 2002. Waited for outcome of Gulf War before starting Oxford APP in mid 2003. First lot of groundschool exams passed with 89% average after shedloads of work (and I mean more work than you imagine!) 107 hrs and CPL skills test thoroughly enjoyable (if frustrating at times) and then back into classroom for phase 2. I know talking to course colleagues that all of us have got seriously fed up with groundschool and struggled to motivate ourselves especially in phase 2. When you're knee deep in those ATPL books it can be hard to see the bigger picture and you can wonder why you started this in the first place.
Make no mistake even just getting through the course is very tough, there will be days when you'll look back on a cushy office job with evenings free to go to the pub, see the girlfriend etc and money to spend and wonder what the heck possessed you!
Do I regret doing it? No I don't at the moment, I have had some amazing experiences flying, met some good people and enjoyed some of the academic stuff. Ask me in 6 months time and my answer will depend entirely on my employment situation. I still absolutely love aviation and flying and this course has only served to confirm that.
It's not an easy decision to make but what finally clinched it for me was the fear of being an old man wondering what might have been. You need to ask yourself the same question. When you're 65 what do you want to be able to say you did with your life?
Good luck,
Desk pilot