Should I just write my novel and then worry about publishers/literary agents or should I think about that before I start writing?
Why bog yourself down worrying about getting a publisher or agent? The first part (which so many people fail to do, actually) is writing a book. I don't know how many times I've heard people say things like: "I'll write a book when the new year starts." Or "I'll write it when the kids leave home." The vast majority of those people never write a book. So, concentrate on the first part first. Or, as they say in my part of the world, "Quit putting the cart in front of the horse."
Write your work first. When you get to finishing the editing/revision/polishing process, then start looking at agents/publishers. Terry