I definitely think you can prepare in that time, any practice is good practice and will reflect in your score. Plus, you probably won’t have time to burn out in 12 days, which was the biggest challenge I faced leading up to my exam. Some of my points have already been covered, but might as well give you my experience, if not simply to reiterate the advice of other posters.
In regards to SJT, if I were to do one thing it would be to read and become familiar with GMC guidelines, and the separate document ‘Advice for medical students’ published by the GMC. I found the latter by far the most useful, as many of the questions on the exam place you in the position of a student, where you have different responsibilities to a doctor, so this advice really helped me to understand what a student would do in each scenario. I made notes on each section of these, highlighting key words which I read back through before the exam. Many people do find the medify videos useful, however I personally found them a bit waffle-y and felt like they sort of just covered the same points as in the GMC guidelines. Although this is only my personal experience, doing these two things took me from a band three literally days before the exam, to band 1 on actual thing. I would also say to just try and do as many questions as possible, as there’s only so many scenarios they can think up - at a certain point they just start to change the names but keep the responses the same! 😂
I also improved my QR massively by using the numerical keypad and calc functions. In mocks before I used the keypad, I would run out of time, end up guessing at least 7/8 questions and averaged approx 500. However once I got the hang of the keypad and M+ / M- / MRC, I sped up significantly and ended up scoring 800 on the actual exam as I could flag difficult questions and actually had time to go back to them. I’d also say that if you don’t see a way into a question within about 10 seconds, just skip it; you’re much better skipping it and answering more questions correctly than having to guess the easy ones because you spent too long on a hard one. ‘Kharma medic’ on YouTube has a brilliant video on the UCAT calculator, which basically saved my life when I was preparing for the exam. You might already be using it, but even practicing to speed up your typing can make a massive difference.
For VR, practice ‘actively’ reading passages. It sounds silly, but I think it’s so easy to scan a passage without actually taking it in at all. After scanning a paragraph, I would mentally ‘label’ it - assigning a key word to sum up the section; this allowed me to consolidate my understanding of each separate paragraph, as well as rapidly refer back to a certain section in later questions.
Good luck, you’ve got this!