If becoming a doctor is your dream don’t give up on it! Math and science courses (especially science) are very important for becoming a physician. It is very competitive to get accepted into medical school, and an important factor is grades. I don’t know about in the UK but in the US and Canada you have to take the MCAT, an entrance exam for medical school, before applying and your score determines whether or not you will be accepted and how good of a school you can get into. This exam is highly based on math and science, so you need to know it well to score well. If you are doing poorly, try to determine why. Is it a lack of interest, poor time management, poor studying, etc? See if you can talk to your teachers to determine why you’re struggling and make a plan to improve. There are great resources on the interent for how to improve studying as well as great tools to help you study in difficult classes like math and science. The most important thing to remember is that if this is what you want, even though it is hard, don’t give up! It will be worth all of the hard work!