what subjects are you taking rn? I'm doing QCE currently in year 11 and had the exact same problem at the start of the year๐ญ
Medicine and law are both super competitive degrees which need high atars, ik a lot of my friends who are wanting to study medicine started UCAT prep throughout the term 2 and 3 holidays this year, while some of them haven't started any prep. I had asked a couple of my friends who are currently studying medicine when they started UCAT prep and quite a few of them said they started pretty late, which they lowkey ended up later regretting as they didn't do as well as they hoped with their UCAT, but had their atar (most of them ranging between 93-99) and interview to fall back on. One of them was lucky enough to get early entry at James Cook for biomed so didn't worry to much about his UCAT. Though this doesn't mean that it is too late to start UCAT prep. Some people are able to only do 1-2 months of prep and still get in the 90th and 95th percentile (score needed for medicine), whereas others need 3-6 months. At the end of the day it really just comes down to what your capable of as a person.
One thing to keep in mind is they both have quite different prerequisites. With medicine you def want either biology, chemistry or physics + methods as these subjects will make it a lot easier to go into, whereas for law you mostly only need english.
I definitely think law and med are degrees that you need to have passion for in order to pursue them or you'll more than likely end up regretting going into them, I would recommend choosing the one that you feel is more interesting to you, as your more likely to do better in it. Also keep in mind that if you do end up choosing just law or medicine you are still able to do a double degree in law and biomed/law and science, so your options are still open in case you want to pursue a career in either one.