Leave off what? People were just trying to answer the OPs question realistically.
Lots of people are the same as you in that they don't realise until they actually come to apply for uni that they don't have the right alevels (and/or grades), and dont have enough work exp. Tbh, part of the onus has to be on you to check requirements as well though. Sure, colleges/schools should and could do a lot more to help. But, at the end of the day it is up to you to make sure you can apply where you want with what you need to have.
Anyway...I would be really cautious about taking animal biology as a route into vet med. It is a way in, but the grad route isn't as easy as a lot of people seem to think. The grad fees are bankruptingly expensive at all but two unis. Notts and RVC arent as expensive, but it is still expensive to do two degrees. Also, they competition for grad places there is very, very, high. Also, many people redo alevels as well. So it may be quicker and cheaper to redo alevels than do another degree first. Just some info for you to think about before you risk the grad route.