BritishGuy is talking garbage. He is looking fom the narrow, purely financial point of view. He is also wrong about the jobs. I know 3 joining Ryanair alone, none with any connections, plus many for other operators in just the last few months, and the number who keep in touch with us as a school are fewer than he claims to have surveyed. The industry is looking much healthier recently. Even have a student with an offer of an interview while he is still in groundschool, although he is the exception as he did know the right people and has unusual background (damned good pilot too).
It depends what you want. Do you want to fly for a living? You will probably never make as much money as you would in you current job over a lifetime career. However you must choose whether any extra job satisfaction is worth the loss of revenue. I think it is to me, having lost a lot by that decision over the last 3 years but not regreting it at all.
Your age is not a barrier (I have taught ATPL groundschool students in their 40s), but you should get our exams done as quickly as possible, to keep career options as broad as possible. If you cannot go full-time, then work hard at the distance learning (it will be tough, having a job as well!).
You could get onto some of the "type-rating to airline" schemes (note I do not necessarily advocate these, just they are an age-limited scheme that publishes the limit) with a frozen ATPL at any age to 35. This suggests your age is not a particular problem, except as it restricts your career hence returns on the investment in training.
Not sure why you talk about 500 hours. Achieve a CPL/IR with ATPL exams (i.e. a frozen ATPL in common parlance) in roughly 230-250, then apply for jobs. Yes keep flying to keep your hours up and keep current (and for fun!), but 500 hours is not a magic number! 1000 hours tends to open a few more opportunities, but they are not the best paid ones so most people are not aiming for that side of the industry.