Great, I want to get into medicine. Now what?

What year are you in?
First step - Get as many 8s and 9s in GCSE
Choose A level subjects carefully, Chemistry and Bio can make you eligible for most Unis. You need Minimum AAA for most universities
In your Summer holidays, start Volunteering, find Care Homes, Old age homes , Hospice , Hospital ward placements
Get some things like Captain role in school, play a team sport , even if its in D team, this will give you lot of points for extra curricular
Look at Universities that ask for Non academic information - Check Manchester, Keel Uni. Try to gather as many non acads points
Choose 4 Universities that interest you, don't think of Oxofrd, Cambridge, Imperial and Kings. Choose 1 Ambitious, 2 Reputed and one Fallback. No Medicine school is easier though.
Once you have chosen 4, look at entry requirements that are common and non common. Start working on them through out years
Hope this helps

https://www.medsci.ox.ac.uk/study/medicine/pre-clinical/applying/reading some useful medical readings for supercurricular! Have a look at some podcasts, bbc health and also BJGP reading articles! I would suggest supercurriculars such as these to boost the calibre of your application and show your interest in medicine. Also personally this is something I did, but entering the immerse education essay competition and writing a medical-related essay as well could be a good example.
Agree with everything @Throwaway2007 said, and once you have sat the UCAT aim for unis where you're most likely to get interviewed based on previous stats etc and cater towards YOUR strengths to really maximise those chances. When you do sit your ucat, I would suggest busting out on all the mocks on medify.
I would also suggest doing things like contacting a GP for work experience, even if it's for a few hours. If you can't do this, try Brighton and Sussex medical work experience which is virtual, or Observe GP which is also virtual and both are free. Look for a lot of webinars online that do free events where they teach you about medicine, mock patient simulations and any events your school may advertise.
Other things would be to participate in extracurriculars that showcase the traits of a doctor:
-Uptake a leadership role in school (prefect? Leader of a club? Initiating your own activities or hosting during opening evenings?)
-Academic interest (As I've suggested, doing research and showing you're passionate about this topic and a motivated student)
-Roles that show empathy (volunteering in school, in hospitals, working with vulnerable people where you're able to adjust good communication skills to a range of audiences!)
...etc, you get the jist.
In terms of picking your extracurricular, i would suggest searching up qualities of a good doctor and sort of list these out and think of doing activities which align with these traits to show you possess the skills medical schools want of you. This would be really useful and pivotal in interviews as they often ask you to back these qualities up with personal examples and experiences!
If you're in year 12, right now majorly focus on your A levels relevant to medicine. You want good predicted grades too in order to be shortlisted by many med unis and expand your options 🙂 I would also look into foundation years if that's what you think would best fit you.
Hope you find this useful and wishing you best of luck