If I learn TCPIP, would it be helpful to me?

IT in general, IT security in particular, is an area where you should always learn. When you do not want to learn any further, then it is time to retire. Therefore, you should already be eager to learn TCPIP, and your question should be: "do I learn TCP/IP first, or is there something more urgent ?" Knowing the internals of TCP/IP is an invaluable tool for understanding what is going on; it is very enlightening. I warmly recommend that you study it. Similarly, I recommend some knowledge of assembly, possibly electronics. Grasping the internal structure of protocols and languages and architectures allows you to keep track of the ever changing field of IT security with much less effort than simply looking at the surface of things.