How to apply to uni when resitting?

Pretty sure i've not done well enough in at least one of my subjects to get into my uni choice, and i'm willing to take a gap year to resit and go to uni a year later.

Does anyone know how applying to uni works when resitting, like are the same predicted grades from year 12 used? Do I have to apply with my achieved grades this year? If so, and some of my grades are bad could I be rejected entry from a uni or would they ignore it as they know im resitting?

as far as i'm aware, if you choose to take a gap year you can ask the university you want to attend to reserve a spot for you for the year after, but they will ask you why you want to take a gap year in order to make their decision

also, if you feel like you may not have done as well in your exams and think that may effect your ability to attend university you can always choose to do a foundation year. this is basically just an extra year instead of the standard 3 on an undergrad course, and their entrance requirements are much lower than standard 1st year entries. some universities lower their grade requirements in foundation years or ask for a lower amount of ucas points, whereas other universities (depending on the course you're choosing to study) just ask you to provide proof of further study (a-level certificates, attendance records, etc)

but if you're choosing to resit your a levels exams, you'll most likely have to defer your university entry/your university will defer your entry and you'll have to apply next year with your new exam results

You need to speak to your exam centre about getting a reference from them if you resit. The referee is asked for predicted grades for any qualifications that you are resitting. It’s up to them what they put or if they put anything. Many resit applications don’t have predicted grades.

Your UCAS application must include both all your completed qualifications and awarded grades (so GCSEs and the results you get in August) plus any resit qualifications with a future award date (so subjects you resit are listed twice with 2 dates).