You have wasted 30 mins writing and procrastinating on this site. Use the revision guides. Your mental health is shot because you know how much aggravation you are creating yourself when you fail totally, and you don't need to. Turn it around.
Procrastination is often a cover for anxiety. Make lists of what you need to do. Put items to do in a box (write down each task) Pull a task out and do one task to completion before you pick another. Make it a pressure game. Set yourself a timer and work as if you have to do it or die (not literally) for 15 mins flat out, then another 15 mins, then another etc etc Start now because its never going to get easier. Turn all distractions off and then reward yourself with something you enjoy when you have completed a task. It's far easier to just idly let the days go by and then you have lost any opportunity you ever had. You will regret not doing SOMETHING right now, and will see all of your pals going off to Uni. You can turn your life the wrong way if you don't grip it, but that is your choice. DO IT NOW