Don't waste your work experience. It's way more important than you think and can make a huge difference to future oppertunities.
As fun as going to a RS or a training yard etc might sound it's a waste of time unless you want to work with horses (like every horsey teenager wants until they grow up and realise that its all hard work and low pay and takes the fun out of a hobby
What do you want to do after you leave school? What type of job or course would you like? Once you decided that you can pick a work experince to suit.