It isnt just 'work experience' that is scored in your PS..
Its elusive factors like ...... 'realistic about what the career entails', 'has insight into veterinary role in farming', 'evidence of ambition/leadership' etc etc.
Unless you present as the type of person they know makes a good vet student and have an informed and demonstrably adult attitude towards the job, it wont matter how many week w/ex you have, because that on its own wont be enough - whatever any Uni tells you.