I would generally strongly discourage taking EPQ, you'll often get much more mileage from just doing better on your A-levels from not spending a bunch of time on EPQ and either having more time to revise or having more time to relax, a lot of unis do not care in the slightest about EPQ, I've gotten offers for chemistry (not medicine, but shows the point) from York, Manchester, and Liverpool, with a C in EPQ. Honestly, unis typically care more about your grades and super-curriculars, which isn't to say EPQ will harm your application, it's just that it's not that beneficial either, some unis absolutely love it, like Southampton or Bath, but most don't care, especially for medicine finding a good work-experience placement will be much better value for time, and same goes for UCAT, a good UCAT score will outweigh any benefit from EPQ
the one place EPQ can really benefit you is giving you the opportunity to talk about something specific, which may give you a slight edge by nudging the conversation in interviews more towards your preferred topics of interest, but that's not something you want to be relying on for your uni application, and it can also help fill out your personal statement if you've run out of things to talk about, but again, just spend your time doing something more interesting than EPQ and you'll be golden, because EPQ is so much work that you can spend elsewhere