- Unless you have equivalent qualifications, you will need to take iGCSEs before A-levels. It's likely you do have equivalents, so it's really up to you whether or not you take iGCSEs.
- In the UK, we use a "predicted grade" system. Typically, someone who knows you academically (a teacher who's taught you for a couple of years is best), will write about a half a page on who you are as a student, and then predict the grades you'll get. Most UK students at the moment will have GCSEs and AS levels, and so universities will look at both of these sets of grades and the predicted grades and give a "conditional offer", where they say to the student "you can come to our university if you get these grades in your exams"