Firstly, well done on recognising the need to repair your education and actually doing something about it.
Is it possible to combine employment with your A-level courses so that you can address both your educational ambitions and your practical need for income? If you can, that might be well worth considering. I sympathise with your predicament, but given your motivation this option might allow you the flexibility to set your own timescales for A-level attainment and possibly a PPL as well, all within a reasonable timescale.
You can also apply for whatever sponsorships (such as GAPAN) and other assistance that may be available. The odds may be stacked against you, but you certainly have nothing to lose, and you stand as much chance as anybody else who shows motivation, commitment, and desire.
You are right, it is a tough industry to break into and I don't think it is likely to get any less tough. I think your broad game plan is a sensible way to proceed at this stage given your resources. If you can combine and accelerate those plans as much as possible (which obviously won't be easy and will need a lot of extra time commitment,) you would probably be doing yourself a favour.
look at night school, correspondence courses, assistance from your local education authority with regards to the A-levels, and at the same time look for employment that allows you to finance (and hopefully save a bit) your life, over a 12-18 month timescale to complete an accelerated course if you can do this.
Also try getting down to your local airport and seeing if there are any opportunities there to find some additional work, even if it is weekend odd jobs. That sort of thing can help you feel motivated, involved, and can in itself open up the opportunity for the odd ride, lesson, or opportunity. It also sometimes provide the resource to "network" with people who can provide valuable information, that may well help you later.