A-level Maths as a mature student coming from abroad

Hello there. I am currently self-studying A-level maths and physics and I want to take the exams and acquire the qualifications (I need them for applying at the university). I am a bit confused with the system. The online courses seem to have a structure of 6 exams throughout the year that count equally towards the end grade. But as a home-studying student, could I sit at just the final exam in June as an external candidate? Would that one exam be adequate to offer me the A-level qualification that I need? Also, what exact exams do I need in maths and physics? There seem to be lots of modules and I am not sure which is the one that I need. Ideally, I would like to sit at the 2018 exams. Thank you for your help. x

Thank you very much for your reply gdunne42. I had a look at colleges offering practicals. I am in the UK and I plan to take the AQA board exams. As you very correctly mentioned, the uni requires practical skills which none of the online A level courses provide so I am on the hunt to find the most affordable option. I am moving to Oxfordshire and I will have easy access to Berkshire and London for the practicals. I just want to make sure that I take the right route, as time is extremely precious (I have 2 young kids). I guess that it will still be cheaper to do online fast-track A-level and take the practicals at a college than attend the whole course at a college. Thanks again and if you have any other tips, I would appreciate them vastly.