Unless things have changed since I applied to uni 7 years ago, Veterinary Science is THE hardest course to get onto. Even more competitive than dentistry and FAR more competitive than medicine.
I believe the reason for this is that there are only 6 universities/colleges in the UK which offer it - and guess what...you have 6 places to put down on your UCAS form! (As I said, things might have changed since then, so apologies if that's wrong).
Because there are so few places and so many people applying for them, competition is tough. Don't bother even thinking about it unless you've been predicted all A's at A level and really have a chance of achieving them. Naturally, there are hundreds of other people out there who are going to get all A's - more people than there are places, so you have to demonstrate that you're different. Which is no easy task.
Here's where the work experience comes in. Start doing it now. And do a hell of a lot of it, and write it all down. Make it varied. Get as much experience as you can with small domestic pets as well as larger farm animals. Offer your services for free if necessary. You won't get in if you've just spent a token week at your local vets. They want to see commitment. So work on a farm, muck out horses and pigs, work as a sheep shearer, work in a cat/dog rescue centre, shadow a PDSA vet as well as a private one.....there are so many things you could do. The more you do the better. And as I say, make sure it's varied. I even heard of a guy who had worked in an abbatoir. As terrible as it may sound, that was probably a good move because it demonstrated that he could deal with death as well as life.
I do not mean to put you off. Far from it, I wish you all the luck. But you need to go into it with your eyes open, knowing how competitive it is. But if you want to and think you can do, there's no reason you won't be one of the elite who make it! Good luck.
And start that work experience NOW! Go on...get on the phone!