Good for you for wanting to try something new!! Hopefully you'll love it. I made the switch several years ago and never looked back. I only use western for trail riding now.
Do you have your own horse? If you do then you'll def be wanting some new english tack. There are a few good posts on here that explain the differences between english saddles as well as an English bridle. It takes some time to get used to tacking up (so much faster for English than for western!) and changing the feel for it but in the end there is so much more of a challenge to it. I think that is why I like it--it truly is harder than western.
I think we have all assumed you know how to ride in a western saddle. Forgive me if I'm treating you like you don't know how to ride, but since I'm not really sure, I'm going to just say that if you haven't been riding/taking lessons yet, def start off with western. It is a good place to begin learning to ride before switching (if you want to, and of course you already stated you do!!) to English. But I think you've already done that! :)
Besides the difference in the tack, learning to actually ride English takes alot of time as well as strength and balance. Even the feel is difference. For example, the stirrups are ridden shorter than on a western saddle, and even more so if you are jumping. You feel less secure in and English, not meaning you'll feel like you'll fall off, but western gives you a deeper seat. The position of your butt in the saddle isn't quite the same. Give it some time to adjust, and you'll love it! Oh and also-Don't buy a suede saddle. They are cheaply made and break easily.
As a side note, I ride in an HDR close contact. I am mostly a jumper myself, but I find it perfect for anything I want to do. I don't compete in dressage, but when I want to do it in the arena or if I'm just working on flat work, I'm really comfortable. I highly recommend it. Also if you are buying your own tack, I would suggest going to a tack store and just trying out different saddles to see how you like the feel of them. After you know your saddle size (again different from western. I believe that a 15" western saddle converts to a 17" English saddle) I'd say shop online. There are alot of good websites that let you buy at discounted prices (http://www.chicksaddlery.com/
as well as Four Winds Saddle Tack Store
Let us know how it goes!!