Hey,
I don't know where Matt went to school, but double check with your Year Leader on the importance of work experience first!
In my school we check on students daily, and IT DOES appear in the end of Y11 report which we attach to their college application!
So if you decide to take Matt's advice and take 2 weekd off, please check that it won't do you any injustice later!
It is true that they will probabily make you do insignificant tasks which may seem a little boring. And that's why you need to make sure that you organize your own work experience if you want to avoid that situation.
What I usually advice my students, is to do some research about companies which deals with what you're interested in (in your case, maybe vets, pet shops etc...), and contact them directly. They may need adult support in which case your form tutor should be able to write a letter of recomendation.
Go and see them in person, and dicuss with them what it is that you are hoping to get out of that experience, and what kind of work you'd like to be involved in during your week with them. Some employers are not very good at being creative, but they will for sure appreciate your initiative!
In any case, don't hesitate to dicuss any issues with them if you are not happy with your work; whatever you do, PLEASE don't just walk out! Everything is a learning experience, and take it for what it is!!!
Good luck with it all, hope you find a good placement!!!