Is there any learning group for QFT?

Oh, you mean online? I'm quite sure you find someone here that's in the same position with you: learning QFT outside university enrollment.

 

Here's a strategy which I know works (at least for Peskin \& Schroeder -- I don't know about Srednicki).

1) Google for, and download, any errata list(s) for the book.

2) Read through a chapter of the book, noting in pencil (in the margins) things you find unclear.

3) Read through the same chapter again, slower, this time reproducing all their calculations in detail.
(Often, these authors skip steps, so you need to work through them so you understand every step.)
Ask questions here on PF if there's still items you find unclear.

4) Do all the exercises at the end of the chapter. (IIRC, Prof Peskin posts handwritten sketches
of solutions on his website, so you can get a bit of help that way.)
Ask on PF (probably in the homework forums) if you get stuck on any of the exercises.


Don't worry about the size of the book. Just maintain the discipline above, although it might
take long time. If you keep moving forward, you'll get there in the end.

 

Yes, don't get demotivated. QFT is a difficult subject, and "one learns modesty in quantum field theory" (G. Scharf in his book "Finite Quantum Electrodynamics").