Just wanted to agree with the above. I'm obviously only going off the info you provided, and I think if you are just wanting to do biochem, then vet med isn't the course you want to be doing and it will not open very many doors into biochem itself. We do a lot of biology in the sense of anatomy and physiology, chemistry is quite limited imo with just needing to understand basic concepts (A Level chemistry was way harder), and we only really had basic actual 'biochem' labelled stuff in the first 6 weeks of year 1 which I think the vast majority of the course chose to not learn because it's not all that relevant and was only a tiny aspect. It is focused on anatomy/physiology, animal health and welfare, pharmacology, parasitology, pathology, clinical skills etc, as obviously the main goal of vet med is to create vets, even though there are options of research etc too I think I'd be very miserable if I didn't want to be a clinical vet at the end, and you also have to do placements before and during the degree which are hands on and nothing to do with biochem. If the idea of being up at 3am, your 10th hour in the freezing cold with a possibly aggy farmer during lambing and dealing with all sorts of fluids and situations doesn't appeal, I wouldn't bother. A biochem degree will be much easier and be focused on your interests. You also can't just 'transfer' onto a vet med degree, you'd have to apply like everyone else and as above, it is incredibly competitive, you need to meet all the grade and work experience requirements, and I'm also not sure on the rules surrounding applying while you are on a degree and not in your final year, so I don't think it's a massively feasible goal unless you are completely dropping out of zoology and taking a year out to do this and are otherwise very serious about it.