Peon ...
Daytripper's comments are right on...You can learn a LOT about special and general relativity along with the basic concepts of string theory, quantum theory,etc, from popular physics books by Michio Kaku, Lee Smolin, Brian Greene,Peter Bergmann, Charles Seife, Martin Rees, and others...I've been reading them for several years now while away summers with lots of time...several hours a day and by the end of a summer you'll make substantial progress.
I buy these, paperback and used at Amazon.com...Have six more on the way right now..two from George Gamow on relativity...If you get their Amazon credit card you may still be able to get $75 in books FREE via a credit from Citibank ...I'm awaiting my first statement...am will look for the credit...
As noted regarding math, you don't have to go thru all the gory and formal mathematical detail of matricies,tensors, Riemann curvature,etc but an explanation of those IS helpful...for example, the description for observing a black hole from infinite distance is understandable,in concept, but once you have seen the simple equation for proper time versus coordinate observer time it's easy to see why this observation is used. And if the math interests you, go for it!
But if you REALLY mean thoroughly, math is a necessity...
One website I found which I like for an introduction to tensors is at NASA:
http://www.grc.nasa.gov/WWW/K-12/Numbers/Math/documents/Tensors_TM2002211716.pdf
it's 24 pages and I was able to get thru 10 pages initially just fine...seemed logical so I hope the last part is as well...I'm saving it for this summer!
I also have Roger Penrose's THE ROAD TO REALITY, a heavy mathematical approach, I think about 1000 pages and while I managed to get thru the first 100 pages or so ok, the remaining 800 were too advanced...but it's been a LONG time since I was an undergraduate EE student...He describes simple things in detail then makes what appears to be huge mathematical leaps without explanation...I am not a fan of this publication...
but I may return after digesting the NASA publication above...
Good luck!