Haha, I did exactly these as my A2 subjects - FM was an AS I took in year two.
English: very reasonable subject, the essay questions in my board (and probably most if not all) can be chosen from a pair or a larger group of questions - they ask very wide questions (especially in A2), which gives you a lot of space to run with whatever you have revised best - so long as you have covered the work in reasonable detail. Don't expect much of a jump from GCSEs to AS - from AS to A2 the exam format changes considerably (closed book - so no text allowed into the exam hall), but if you actually revise like you are supposed to, not having a book to be distracted by actually helps you focus your response - you're not tempted to run off and look for slightly more applicable quotes, for instance.
Maths: I'd say this probably has the largest jump from GCSE to A level. Know your GCSE stuff before you start. Our college made a huge emphasis on getting everyone up to speed with GCSE material right at the beginning of AS because they knew some of us were from ****e secondary schools that couldn't teach maths properly (I could rant for longer).
Economics: Really simple subject at A level throughout A2 and AS. Get your head around the theory by applying it to practice questions where you can and you'll be fine. For AS, memorisation is actually quite important: definitions and basic analysis make up a considerable part of the AS marks. In A2, that sort of drops away and it becomes a question of you being able to apply knowledge. Also, A2 (at least under OCR) is very synoptic, meaning that a good deal of your AS knowledge will be required for A2 - don't be put off by this, it actually means you don't have to learn too much in year two, you just need to get really comfortable applying what you already know to given contexts. For OCR, they do a stimulus material pack for their A2 macro exam. This was released last September for this summer's A2 macro exam; if you learn how to read it properly, you can guess a good number of the questions that will come up - I did this for the 20 marker and had preplanned it, so that in the exam, I don't think I would have missed out on more than two or three marks on the essay.
Further maths: Don't do this unless you are able to juggle 5 subjects at AS or 4 subjects at A2. Many of the courses that actually require FM at A2 recognise FM and Maths as one A level, rather than two. So you'll likely be taking up 5 AS subjects and 4 A2 subjects. I thought I could handle that this year, I was proved horribly wrong - luckily it didn't count towards my offer. AS further maths, despite my failures, is actually relatively easy. I've heard that FP2 and FP3 is where it gets tricky, however, so be warned. If your college offers FM as an express maths type thing, where you complete your A2 mathematics in the first year and then work through further maths, remember that you will be applying to universities with the final grade you score in that summer in A2 maths. If you flop your A2 maths, even though you can resit, it will already be a black mark against your application. Whereas, if you can only do AS maths and AS further maths, if you are able to juggle, as I've mentioned, you should be able to score two solid grades in these - actually bolstering your application by giving you the advantage of an additional AS.
My subject recommendations for various degree entries:
Economics: Economics, Mathematics, English Literature + Further Maths AS (or, if you are applying to LSE/Oxford/Cambridge) FM A2
Law: English Literature, History, Mathematics - you may also want to consider just doing law as a subject. People on here slate it by claiming that universities that offer law will teach it from scratch, and that the law A level is a bit of a soft one. I would call bull**** on that - I know of two people who have offers for Law from Oxford and LSE respectively who both took law through to A2.
Business/Finance: Don't do these subjects if you can really help it. In terms of gaining a job in banking/finance, employers are more interested in your skill set than your pre-existing knowledge of the industry. That's why a lot of people who take maths and physics gain highly quantitative jobs in finance - even though they'd probably never heard of equities or fixed-income until Goldman Sachs paid a visit to their campus and mentioned the starting salaries they offer. That's why I'd argue it'd be a better choice to pick something that forces you to improve these skills, rather than something that is highly applied content-wise. (Note: your knowledge/experience of the industry can be gained through internships etc.)