i think liverpool has the highest work experience requirements so if you meet their requirements you're sorted for the other unis!
liverpool asks for 4 weeks in vets practices and 6 weeks other experience
i've personally found my non vet work experience to be the most useful, lambings great! and i loved the dairy farm i worked at too
its good to have a wide range of things, for example, kennels, dairy farming, lambing, working with horses are all really useful, also if you can get a long term placement it shows commitment, like i've worked at a donkey sanctuary/animal centre for the last 5 years!
there should be a work experience thread around somewhere thats got loads of peoples different experiences in that should help if you search for it!