Grotbag -
a) If you can afford integrated is it worth the extra money?
It depends who you ask. The answer from anybody who took the modular route is usually a resounding 'no'. I opted for integrated - so I honestly hope it is worth the money. I'm not going to say 'yes' because anything can happen, but I did my research before commencing my training over a year ago and I still believe now that my chances of employment with an airline are much higher than they would have been had I opted for modular. I've seen CTC's hold pool completely empty a few months ago, so hopefully by the next seasonal recruitment drive there won't be a long wait between finishing my training and getting into that right hand seat.
b) If you chose modular, could you fit training around seasonal or part time overseas work?
Yes. You can do pretty much whatever you want.
c) If you studied full time for a modular course instead of integrated what are the differences aside from one's residential?
You save a lot of money by doing a modular course. Other significant differences include your flying school's connection with airlines, and ultimately your employment prospects. Spend £50k on modular and attempt to make the money back with difficulty, or spend £100k on integrated with (in my opinion) a much better chance of clawing your money back in the short - medium term. You need to consider whether the extra £50k is worth a better chance of employment at the end of your training.
d) How much of a benefit is it to have a few years life experience and responsibility when applying for your first position in the industry?
I am mid-twenties at the moment - having had study and work experience (some relating to the industry) definitely helped me. The only other way it will really benefit me is that I can probably return to a previous employer if I can't find an airline job before I have to start paying the bills again. The selection for CTC involves an interview, so it is unlikely that I will have to sit an airline interview before placement with an airline.
Good luck with whatever you decide to do!