A-levels are academic qualifications that are subject based. If you want to look at some of your GCSE subjects in more detail alongside new subjects then this route might suit you.
A-levels involve lots of reading and in-depth research about your subjects. You should enjoy this approach to studying and be happy taking exams. You would usually select 4 subjects, you can take subjects you have previously studied at GCSE, start new subjects or select a mixture of both.
When you choose your subjects try to pick ones you think you will enjoy, be good at and if you are interested in a particular career, check out the entry requirements to see if any particular A-levels are essential or desirable.
As a general rule, you will need at least 5 A*-C grades including English and Maths to take A-levels but check entry requirements carefully as they do vary and many colleges/sixth forms require a number of B grades for entry and ask for at least B grades in your chosen subjects.
Which? University has lots of useful information about A-level choices.
Don’t forget you can see a your careers advisor if you are unsure and want to discuss your options further.