There's more to riding English and jumping that switcing tack.
I would recommend that you take some lessons at an English lesson barn so you develop a secure jumping position and some experience in how to handle an approach and landing from a fence.
Then, I would get a more experienced English rider to start your pony over fences. When your pony is going well for the experienced rider, and you're confident in your lessons, is when you should think about jumping him yourself.
Green pony + green rider = black and blue rider