I'd imagine you're wanting to aim for a Paramedic Science degree. Your A levels are great and will put you in a good position when applying as they do ask for a science with preference on Biology.
If you think it's getting stressful, perhaps spend an extra year in college by resitting the year or switching an A level (although keep Biology) - be careful with this however as universities such as St George's do ask you complete the A levels in 2 years, but for most this is not the case.
Don't stress yourself out, have a look at the other qualifications they accept and the grades you need and consider them, even if it's once you've finished college. There's still some funding available. Don't worry about what people think you're more/less capable of, do what's in your best interest to graduate with a Paramedic Science degree and subsequently, HCPC registration, as that's what really matters if you want to practice as a paramedic, not peoples speculations.
You'd find there's a lot of mature students on a Paramedic Science degree so there's no need to feel you're falling behind if you don't go straight to university - there really is no rush. Any voluntary/paid work experience in a care environment to help yourself establish your understanding, desire and true intentions for pursuing paramedicine will help and will certainly give you things to talk about in the interview, but anything you can make relevant to the role is great too, so taking some time out for this may be useful. Likewise with things like gaining a full UK driving license if you don't yet have one (another requirement, although some ask for it by X date after commencing on the degree) and getting your C1 provisional license.
If you have any more questions, feel free to ask.