EPQ

hello! when i was doing my epq, i was shown an example of someone who rewrote a text that got a top mark, so it's definitely something that's achievable!
the main downfall here is that there will be a word limit (usually 5k +/- 10% each way) and novels, assuming that's what you mean by book, are usually 50k+.
for my exam board (which was eduqas), you could do a creative project, like writing a story, but it had to be accompanied by a reflective report, meaning you don't have the whole allowance of 5k words either. so a short story or something with a definite word count may be much better than attempting to write an entire book - not just because of the workload on top of completing alevels but because you cannot submit a piece so long unfortunately.
it's still a research piece too, so you might want to start reading around and seeing how medical scenarios are portrayed by different authors or settings etc so you can pick up on conventions of the genre. this could then be mentioned in your report (e.g "i utilised metaphors here because x author did something similar to get x idea across), and will show that you have researched your topic properly!
do consider if this is gonna be too big of a project though, cause you do have less than a year to do everything. best of luck, this could be a really good project idea that would make you stand out in applications!!