Yes it matters. I failed my A levels miserably (mainly through spending too much time with my wife) and had to do things the hard way, re-take, foundation course (no degree, as my father couldn't afford the 3/4 years maintenance, which by today's standards was cheap), 4 year student contract only to be made redundant when the market fell through in the early 90's.
Having said that, the A-levels are a means to an end and not special in themselves. But fail them and (from experience) you continue to have nightmares about exams and results, even after 30 years of working, when they no longer matter. An absence of good A level grades just makes it harder to get where you want to go.
Cut to the present day and I'm vicariously living through it again with my eldest. Fortunately he took my advice and put the work in to get the grades required.
In terms of recruiting, I now make use of A-level entry candidates for apprentice positions with a view to studying AAT (and sometimes ACCA thereafter), so they remain the best indicator, both in grade and subject, of a person's ability to pass their future professional exams.
It depends where you are based, but given the introduction of the Apprenticeship Levy last year, the bigger services firms (not just the accountancy firms) are investing more heavily in apprenticeships which would be a good starting point for you to do AAT and then ACCA or ACA. Age or experience is not a barrier, but qualifications, ambition and aptitude are. Don't forget you will be starting at the bottom again and this can be a stumbling block for some.
I would have a good think, even at this stage, about the area of finance you want to specialise in and the route you want your career to go. It could be a waste of (your) resources if you train as an accountant and then end up wanting to be a money broker, dealer, stockbroker or financial services/insurance expert which may have a different training route. Pick your specialism first and target those companies or firms for a training or apprenticeship role is my advice.