A level advice for a new year 12!!!

I’m taking Biology, History and English Literature and I will put in my all to get three As and above as I aspire to go to Oxbridge or Kings for History and politics or international relations or Philosophy, politics and law. Please give me all the tips possible and how I can go above and beyond to not only get into the university of my dreams but also to get the best grades possible as I know I can achieve them. Also any tips for how to research for history would be great and supercurriculars for the courses I would like to take in higher education would be great. Thank you so much in advance!!

Hello! I do History and English too.
History: Make your flashcards/resources as you go along, as the content piles up quite quickly. When you start fully getting into exam revision later on, planning essays is a really great way to do it, as you're going over the content, applying it, and preparing for the exam. You can write some under timed conditions too, but the more you plan the more prepared you'll likely be.
English: Put quotes (both from the texts and from critics) around your room/house in places that you see a lot. Again, planning essays is super great. Make sure you re-read your texts; once in class, write a chapter/act summary sheet, and then re-read the most important chapters/scenes again later on. I'm not sure what exam board you do, but I assume you have to do coursework in year 13 with chosen texts (if you don't then just ignore this!). Try and choose your texts and your focus during the summer between year 12 and 13, just to save yourself a bit of time and stress in year 13.
For extracurriculars, Model UN, debate, student leadership (e.g.: School Parliament, Head Pupil), and newspaper are really good for your subjects. Id your school/college doesn't have any, ask to start it! That'll show your involvement in the school and your interest at the same time.
Most importantly though, try not to get too worked up about uni/grades (easier said then done, I know). It's awesome that you have big goals to strive for, but remember that you are a lot bigger than your education. Take the time to research different unis, and make sure that you find one that is absolutely right for you. If that's Oxford/Kings, then great, if not, then also great! And, make sure you pick an insurance that has lower grade requirements, but that you also really like, just in case. Keep at the very least one full day a week where you do no school work, and set aside time everyday for hobbies/socialising/relaxing. Especially at the start of year 12, since you have nothing to revise just yet. You don't want to burn out!
I would also suggest (it's not relevant to you yet, but when it is) writing your personal statement during the summer between year 12 and 13. Oxford obviously has early admissions, and you don't want to rush it. You can of course go back, redraft, and get feedback, but if your first draft is done before September the hard part will be done.
Good luck, and I hope you enjoy your subjects!!

I’m taking Biology, History and English Literature and I will put in my all to get three As and above as I aspire to go to Oxbridge or Kings for History and politics or international relations or Philosophy, politics and law. Please give me all the tips possible and how I can go above and beyond to not only get into the university of my dreams but also to get the best grades possible as I know I can achieve them. Also any tips for how to research for history would be great and supercurriculars for the courses I would like to take in higher education would be great. Thank you so much in advance!!

Heyy, I also really struggle with procrastination. I think the most important step is realising why you’re procrastinating - are you overwhelmed by the size of the task or how many things you have to do? Are you afraid of your lack of perfection in a certain task and therefore prolonging doing it? Etc
Decide on specific times you will work/how long you’ll work for, and stick to it. Giving yourself some time everyday is crucial if you want to have a sustainable work/life balance. E.g I always make sure to have an hour after school to do something I enjoy/non school related, and always stop working at 9pm so I have enough time to sleep. If you overwork yourself you will inevitably only associate school work with being overworked and exhausted.
Take care of yourself! From someone who applied to Oxford a few days ago, it’s important to be consistent with your work but also with your own wellbeing. Don’t lose yourself!