No offence, and I'm not trying to question your dedication here, but you sound like you're still a little undecided about the route you'd like to take after sixth form. A lot of people still don't know which course they'd like to do, but biology and English literature are very different and the fact that you'd be 'okay' with either would suggest that perhaps you should look a bit more into it. Do you have a particular career in mind?
Do you think you can identify why exactly you didn't do as well as you hoped? You mention that you think it was only one chemistry paper which bought your grade down. This would imply that your performance in this paper was down to a possible lack of revision, as if it was due to genuine struggles with understanding the content then lower grades all round would be expected (well done on your A in the coursework!
) You do, however, say that you would have to 'struggle' on with A2 chemistry, which gives off the idea that perhaps you're not enjoying it and perhaps it would be best not to continue. Bear in mind that depending on what sort of biology you're studying, it may well have links to chemistry (in my AS course a large chunk was dedicated to biochemistry, and I'd imagine that this is studied in finer detail at degree level), so if you don't really enjoy chemistry then perhaps biology may not be the course best suited to you.
It looks as if you've put a lot of thought into your options, but while you've described your situation in detail I don't really want to be picking what you should do based on what I've read here. It's for you to decide, based on what you want to do later. If you're certain that biology is the path that you want to take then 1 sounds like the best option in my opinion, however if you end up thinking that English is more your thing then perhaps 3 is the better choice. Personally I'd advise against 2, as an entire A Level has a lot of content and it might be a struggle to do it all. 4 sounds like it could also be a contender, but as you say that would sadly mean spending an extra year at home. Bear in mind though, that while leaving your friends to go off to university may sound unpleasant, going to university to study the wrong subject only to drop out after a year and leave all of THOSE friends behind would probably be worse.
Sincere apologies if anything I've said comes off as a bit blunt, I didn't intend it that way, I'm just trying to get you to decide for yourself which path you'd be happier with, biology or English. I wish you the best, whichever you pick