Looks like your out of luck, most people in your circumstance do the extra year at the beginning of the degree (Access to higher education or whatever).
You are best speaking to the targeted University itself, they are are exceedingly helpful with mature students. I've known a few people go down incorrect routes, its best knowing exactly what the University wants and what they can offer.
If you just want to do physics A-level by itself, provided your maths is reasonably ok, I'd be tempted to get the books and do it that way. Don't use online courses unless they are from a formal place of education.
If you've got a decent memory and maths, physics A-level is quite easy. Degree level physics is a lot of maths.
Have a look at the Open University, may not need the A-level with them.