Most of today was spent trying it out on my perch, and I was quickly amazed by the results! As advised by Alex Berryman I had the F-stop at f/8, which really brought out detail, and still left the background out of focus, actually, I'm amazed at just how smooth the background was on some of the shots. The shutter-speed was relatively slow -around 1/80-1/100- as the garden was still in shade but I managed to get some decent results, compared to what I was getting before they were amazing! I also had the OS on level 2, and ISO between 800-1600.
I'm glad to say that besides my perch, I'm going to start a new project, this one on Jays! It's a simple little setup; I made a small log pile with Birch at the front, and dug a small hole, about 1" deep and 1-1/2" deep, this I filled with Peanuts, which today the Jay has been taking! I believe it is taking advantage of this food to cache for the colder months ahead. I have already managed to get my best Jay shots yet! Which I am very pleased with, hopefully we'll get some properly nice light soon!
So, so far it's an amazing lens! Glad I bought it!