The Pony Club have theirs on the website so if it was just for practice, you could use those. They vary in difficulty so you can pick which one you want to use.
I just got some last week. You order them from British Dressage - off the website. Between 50p and £1 each per test and they post them to you. I presume trying to get them anywhere else would be a breach of copyright - for for the sake of a couple of ££ I would just order them from BD.