Where have you been resident for past three years, and where are your family resident? An English national whose has been living outside Europe for the past three years might well be treated as an international candidate, liable to pay the international rate of university tuition fees.
Each university sets its own entry conditions for each course, and will usually specify alternative entry requirements for those candidates who do not have A-levels. However, entry for most UK universities must be via UCAS. If you want to start studying Sept 2015, you must submit a UCAS application form, naming courses at up to 5 universities, between 1 Sept 2014 and mid-Jan 2015.
Just as an example, have a look at say Economics. As suggested, go to Which uni at http://university.which.co.uk/
and search for Economics. The first one listed is LSE, which simply requires 3 A-levels, any subjects, except that one must be Maths at A*. If your French course can be compared to the IB, you might find it easier to check the IB requirements of 38 overall and 7,6,6 (again in any subjects), provided that one of those is Maths at 7. If you scroll on down, you'll see that there is other info about the course, such as that 36% on the course are from outisde the UK.
You can also look at the university's own web page, at:
and choose prospective students and undergraduates.
Note from this page, http://www.lse.ac.uk/study/undergrad...uirements.aspx
, that LSE have a list of "non-preferred" subjects at A-level, and prefer candidates to be studying a range of subjects. Maths and Sciences would therefore be fine for LSE.
LSE (as do other universities) also provide a lot of detail about each course - for instance see http://www.lse.ac.uk/resources/calen...cEconomics.htm
), and it is a good idea to attend open days once you have whittled down your choices.
You will need to do quite a lot of research to find out which courses at which universities you would be interested in studying.