Some schools used to give out a certificate say you had completed an approved course. But I have never seen one since and mine went in a bucket 2 mins afer being given it. You will get your exam pass/fail certs through the post.
I haven't had to show mine to anyone ever. When you book your flight tests the CAA computer knows all about you so if you don't have them you won't get a test date.
Just phone up the school you are going to and ask them what they want to see.