Hi there, I just this ear completed a level 3 extended diploma in Engineering (without an A level). I achieved D*D*D* (including distinctions in maths for technician s and further maths). I personally have found for the majority of university's courses, this grade was actually overkill and they will take something in the region of DDM. From my experience it is only really the top 10 or so who specifically require A level maths alongside it.
If you want to get in to one of these top universities, then you will need to find a way of achieving your A in A level maths, however if you don't mind going to a uni outside of this ranking, then a good grade in the level 3 extended diploma will be fine.
When applying for unis I got 4 of my 5 choices (Liverpool, Newcastle, Sussex and UWE), however Manchester (ranking high for the subject I chose) required an A level maths test at their uni before they would accept me. And this was using my predicted grades, which are lower than what I got.
My best advice for any apprenticeship or uni applications (apprenticeship especially) would be to do some form of work experience out side of academic time, as they seem to value that very highly (i workers part time at a marine engineering company and did various work experience weeks with BAE)
Hope this helps,
Liam