Taking A Levels independently age 20 - Help with advice?

Hi, first of all I am wanting some advice on taking A levels again independently, I did them when I left school at 16 not knowing how hard they really were, silly me. I'm currently 20 and now doing an apprecticeship, I've will have completed my level 3 in 5 weeks time and now looking to start a HNC, paid by my employer. However I have the mindset that I don't see myself doing what I am now (electrical engineering) as sometimes I feel the job isn't for me. I know some people may say stick with it but I've always had the intrest in Physics and space.

I did maths and physics back at 16 and failed as I never really put the effort it. After a period of being down because of my grades I picked myself up and went back to college for biology, chemistry and psychology. Ended up droping out because of personal reasons, but I was doing alright in these.

So I have looked at a few places to do the A levels maths and physics again ready to be more determained to pass them with good grades knowing how much effort to put in if I really want them. The places I have looked up are the oxford college as well as, ICS that I saw from a post 4 years ago on here recommending them. However I've seen people have had problems with the Open College and dont know whether they are good or not?

Firstly, I am thinking of starting in the next month to get a head start on before the septemeber students. I was wondering if someone could give me some advice on the oxford college. On the website there is a fast track physics which I understand is done in one year, I was wondering if anyone has done this before and gave let me know about it? Is it best to do the fast track I was thinking I will be really committed to it.

Secondly, I was wondering as the A Levels would take me at least 2-3 years to do, around part time around work, would universities let me on a physics degree course if I were to complete my HNC with the UCAS points and the 2 A levels? Or would I have to study for a third A level?

Lastly, for anyone that has done maths and/or physics externally could you recommend some books, study habits, experience and advice on actually getting into university this way.

I know long post but I just wanted to explain it as best as I could. Thanks in advance.