Sadly, Morgo your circumstances are not that different from many other people's.
I'm afraid you might need to do a bit more research as to the options available and how you aim to get there!
You may have to factor loss of earnings into the equation at some point - how will you do the commercial flying training - that, I believe has to be full-time. I'm sorry but I do not understand how an employer can charge YOU for time off? If that's what you lose as income, then that is part of the cost of getting what you want.
As I said CPL may be your route but it won't get you into the airlines as there are no Instrument Rating exams in the CPL. However, it would be sufficient if you plan to be an instructor.
What sort of job do you envisage getting as a pilot? Have you looked into the career openings 'cos, as I understand it, it ain't brilliant in the fixed world either.
Cheers
Whirlygig