Above is correct that most of the unis want higher GCSE grades than you currently have - most of them care more about the subjects you get the grades in, but a lot also ask for a specific number of grade 6/7s too - Notts ask for 5 grade 7s, Liverpool asks for 7 GCSEs at least AAABBBB, I don't think Bristol care so much about GCSEs and only ask for 4s+, essentially all unis have different requirements and you'd have to research into them individually (all the UK unis are; Nottingham, Liverpool, Harper Keele, RVC, Surrey, Cambridge, Glasgow, Edinburgh, Aberystwyth).
I'd say that your best bet would be to resit your GCSEs which you most need, i.e. sciences, maths, English to get at least 6/7s (7s most important in chemistry and biology) to be eligible for most amount of courses as it is incredibly difficult to get into vet med - I am a reapplicant as I was unsuccessful last year. However, if you're not far off it doesn't necessarily mean a strict rejection, in my GCSEs I got 6s in maths and physics which were my lowest 2 grades, and I didn't want to resit them. This limited me in where I could apply last year (also with work exp requirements) as for example Nottingham asked for a 7 in either maths or physics, but this year I applied for the normal course and got through to interview stage despite not having these - albeit I've got higher A Levels of A*A*A now so may be why it was forgiven, but I've heard of many stories of people not reaching GCSEs slightly and getting through. This isn't something I'd bet on however, I'd make sure you have all the correct grades for the best chance, and many people do resit their GCSEs in Sixth Form for this reason.
Another thing to look into is gateway/prelim courses available at Nottingham, Bristol and RVC, and their requirements for GCSEs are generally lowered. But these have less course spaces, are a year longer and you do have to reach the widening participation criteria to apply.
Best of luck, it is a tough journey going into vet med but if you work at it you'll hopefully see results.