The RT Practical test was, I recall, a lot easier than I expected it to be. The pre-test briefing told me everything I really needed to know, and the hardest part was really getting my RT head on. I found that sitting in a small room at a desk rather than sitting in an aeroplane, doing RT just felt out of context for me so I didn't quite get into the right frame of mind!
If you're happy with using the radio when you're flying, the test is pretty straightforward, and the only bits you may find unfamiliar are the mayday and pan calls, but again, those are covered in the briefing (at least they were on mine!)
Good luck!