Your have chosen a tough but worthwhile area to study riaraj, medicine is as you would expect a long tough road before you qualify to practice, and even after that requires continuing study to keep up to date.
So you have to start somewhere and you just happen to be at probably the perfect age to lay down the foundation stones to get you into university.
You will ideally need good results in most of your gcse's with emphasis on chemistry and biology, where really good scores will help you at sixth form college.
During summer holidays and weekends, volunteering at maybe a nursing home, local clinic or hospital will give you an idea of what is involved caring for and treating people. Your tasks may be menial like making tea or accompanying visitors to hospitals departments, but just being in the environment and chatting to patients and staff will be valuable and useful to bulk out your personal statement later down the line.
It is a long journey but takes one step at a time to reach the end, so put in the extra effort these next few months and try hard to ace the subjects most required, and maybe look on TSR for previous years papers to practice on.
Good luck and fingers crossed