Of course, I have a vague idea but currently I’m interested in studying five subjects (English literature, French, history, German and maths) but I don’t really think that is an entirely feasible option.
I know little about the precise amount of work each of these subjects involves or any specifics about the course content so I’m hoping an open evening in the new year at my school (where I am staying on for the sixth form) and a prospectus might make it all a bit clearer. I want to know a bit more before I commit myself to anything. The ditherer in me is insanely pleased by the fact I’ve been told option choices can be changed pretty much up until the end of September, which makes me feel fabulously reassured.
Just to reassure you further, I know loads of people who changed subjects well into October and even November, so you definitely don't need to decide yet. If you're unlucky, you may find there'll be a timetable clash between 2 of your subjects, which would kind of make the decision for you!
Judging by the fact that you've taken GCSE maths a year early, I'm assuming that you're very intelligent and academically capable, so you may want to consider taking 5. As you can tell from my sig, I do 4 (including 3 of the ones you're interested in taking) because no-one in my school ever does 5; 4 is the absolute maximum! I find it quite a lot of work and I know I wouldn't be able to handle doing 5, but then it might be different for you, especially as you'd have one non-essay subject. If you think you might later regret not taking them all, and if your school allows it, you could always do them all to start with and drop one if it's too much. Otherwise you'll have to make a decision. It's fine to use mock grades to help you decide to a certain extent, but remember that mock grades are often quite different from final grades, and with all the work involved in A-levels, I wouldn't recommend taking any subject unless you really enjoy it, even if you're good at it. If I didn't love all my subjects, I'd never be able to motivate myself to do so much work.
Obviously subjects vary according to the exam board and syllabus, but I can give you some general information about English lit, French and history (all of which are Edexcel for me). English lit is not too different from GCSE except that you can't blag it anymore and you do need to write plans, but that's true for all essay subjects at A-level. In terms of the actual content, I study a play called 'Translations' by Brian Friel, the Edexcel poetry anthology, a novel called 'Hard Times' by Charles Dickens, and for coursework I'm doing 'Much Ado About Nothing.' Pretty much the same types of literature as at GCSE, the only differences being that for poetry, you use more technical terms and you need literary criticism by other writers and for the novel, you need to go into more depth about things like characters, themes and settings. The workload is quite intense, but you get used to it and it's interesting.
French is my favourite subject, just like it was at GCSE. The small class takes some getting used to because you have to read out loud and answer on-the-spot discussion questions all the time, but the teachers speak mainly French to you and you have an assistant to help you all year instead of just for a few weeks before the oral. It's a huge step up from GCSE and you'll probably panic at first at how hard it is, but it gets easier and is really enjoyable and rewarding. The listening tapes are about 10 times faster and the reading questions try and trip you up a lot more, but there's no separate writing paper; just writing questions on the reading and listening papers. You have to choose and research your own topic for the oral, and the only rule is that is has to be something do with French culutre/society, so it can be almost anything you want. You do a 1-2 minute presentation and then have an 8-10 minute discussion where the examiner asks you some unexpected questions that are related to the topic, but not necessarily to what you've talked about. (Your exam structure may vary slightly if you're with a different exam board).
History isn't that much different to GCSE, except obviously in more depth. There's a lot to cover and the timing in exams is a bit stingy, but you still have one essay-based paper and one source-based paper as well as coursework. My topics are Weimar and Nazi Germany (source), Fascist Italy (essay) and Origins of the First World War (coursework). It can be boring at times and one of my teachers isn't exactly brilliant, but most of the time I enjoy it.
Sorry, I didn't think this was going to be so long! Anyway, I hope it's been of some use, and feel free to PM me if you want any more information.