The previous poster covered a lot of other stuff really well so I won't touch on that!
As for EPQ, it is never a required qualification however some universities do offer a lower entry requirement for certain subjects if you get a good enough grade in it. When picking a topic/title, make sure it is a subject that interests you and make sure you can be evaluative with it, not just descriptive. E.g. You can't just explain how a thing works for an EPQ, you have to have different sides to an argument or different approaches you can take, weight them up and compare them against each other and come to a conclusion. I did my EPQ on using bacteria and viruses to treat diseases and got an A if you would like anymore specific advice, I'll try to lend a hand!
Career options wise, the importance of IBMS accredited for NHS positions has been covered. However other options are still open (with ot without IBMS accreditation) such as in labs (e.g. Research), non-lab based science roles (e.g. Working in the admin side of a science company, clinical trials), and non-science based jobs at all. A biology degree teaches a lot of skills that cover a lot of jobs!
Books wise, there's a lot out there and it depends on your interests but one I have read that I loved was The Beautiful Cure by Daniel M Davis. It talks through advances in immunology looking not only at the science, but how they got there, the things going on in the scientists lives around that time, the weird science politics of research and Nobel prizes. I dont so specifically Biomed (but a different biology-related degree) so it might not be completely what you're looking for but I found it really enjoyable and interesting!
I hope this has helped in anyway and please don't be afraid to ask anymore questions!