So I recently purchased this-

(The Union Flag Version)
I'm fairly certain the actual British army doesn't wear that exact type, but I am curious as to where they would wear them. I have searched around, but I still can't be sure.
Is it just on one arm? The left or right one? Whereabouts? Smock? Shirt? Both?
I know it won't be exact because the flags different to what the British army use (I'm fairly certain at least), but I also figure that because its different some people won't find it offensive?
I have reason to believe that it is on the left arm?
Thanks in advance.