I would start with the new 52 when it comes to Batman, was essentially a reboot for the DC universe and Batman started again as well, I think the first two volumes are out, other great books I recommend are The Long Halloween and it's sequel Dark Victory, amazing set of books.
As well as Batman Year One, a great origin story for the Batman, well written and interesting art.
The Walking Dead compendium would be great for you, I've seen the first two in Waterstones and both are massive and full of issues. Probably cheaper online though, as almost all books are. If you want to get them gradually though the trade paperbacks are super cheap, but obviously don't hold as many issues, plus I believe that all the front covers join up to make one big picture!