I am looking for good textbooks for lattice and coding theory. Lattice and coding theory are very interesting on their own, but I have application of the theory to K3 surfaces & modular forms (and vice versa) in mind.
My goal is probably to go through Conway & Slone's "Sphere Packings, Lattices and Groups" but the book is too difficult for me at this point (the book is a collection of research papers). I have read roughly half of Ebeling's "Lattices and Codes", but it is getting harder and harder.
I would appreciate it if someone could introduce good textbooks to me. Expository articles are also welcome.