Well, as you are probably learning in your course, classes are usually broken into a few different areas. Listening and Speaking are usually put together, and Reading is usually paired with Writing. Then, there is just straight Grammar. Often these consist of a core, with three classes each day. On top of that, there are elective classes, which can be anything really. Two basic ones might be Pronunciation and Idioms/Phrasal Verbs.
There are a few major publishing companies that will have books that appear in a series. You can look on Longman, Oxford, and Pearson websites for those texts. Often, you'll be able to request a teacher copy for free to evaluate the book. Trust me, some of them are real stinkers. Some are teacher friendly, others require people who really know what they are doing. One book that some people like--not me--is called "Speak Up." It has a lot of open-ended questions that are supposed to lead to discussions. There is a textbook series called "Tapestry." I like this one, but it is pretty formal, so it's like being in a school. Another series is called "Northstar." It has a lot of problems, so I'd steer clear of that one unless you are solid on teaching. My favorite L/S book is called "Interchange." It builds the language systematically, allows for creativity, addresses a bit of everything (L/S, R/W Pron/Gr), and if done correctly will really take
students from one level to the next. The competing series for that one is called "Passages." It's similar, but maybe it's more British? I've not used it much, but it seems like sometimes it throws too much at the students at once. Either you let them be a little random, or you only do certain portions of a page at a time, and thus skip around a bit. I believe that language is like building a house, so I like to follow structure and build. To me, randomness doesn't spend their time well. Then again, I've not used it too much. I suppose others would say that "Interchange" doesn't have enough in it. I like to supplement, so I like Interchange. For example, in the food chapter, I have them use the target language to make a menu, and we have a potluck. This would work great for a church outing.
The most famous grammar book that I know of is by a person called Betty Azar. I think the actual title is "Fundamentals in Grammar." I just call it Azar. It does what it needs to do, is clear, and most important, ACCURATE. There are grammar books out there that actually give incorrect or misleading information. As an example, one book said that "Been" was the past participle. To be correct, "BE" is a verb. The participle is "EN." That really confused students. So, be careful about grammar books. Azar doesn't need to be fixed or modified. Another grammar book is by Ramond Murphy. If I remember right, it also was accurate, but less dense than Azar. There is one called "Focus on Grammar." It has readings, and those can be turned into writings; however, you'll have to supplement the grammar parts, as they are lacking. By the way, Azar is mostly fill-in-the-blank, which can be boring, but it does have question parts.
I like to use Graded Readers. They are books that are famous that have been edited down to create different levels. There are two publishers: Penguin, which is usually "American," and Oxford, which is usually "British." Remember that vocabulary, spelling, and cultural cues will be different for Am/Br English, so pick them wisely. You can do a book club, and create questions for them to answer with partners, have them create alternate endings, write book reports, compare characters etc. These are incredibly useful if you just use them with an end product in mind.
I don't like R/Wr books because they don't really spend enough time on writing, so you end up with a lot of random garbage. I'd separate them. A great writing series is, I think, called "Fundamentals in Writing." I think it's by Ann Hogue. There should be three colors, yellow, blue and orange. It has activities for each chapter, and can really teach students the difference between different writing like descriptive, narrative, expositive.
You'll want a good picture dictionary. My favorite is the "Oxford Picture Dictionary." I like the oldest edition the best. It's clear, simple, and to the point. I'll often get it out and show students pictures of things that they don't know, such as vegetables, animals, musical instruments etc. I'm old school, so I prepare for the lesson well. Thus, I don't need students to be using the Internet during class to look up pictures. I also find it annoying to wait for them to scan and search, as it puts them in control of the timing of the class, which is essential for a well-run lesson.
As far as pron/idioms, well, I'm American, and I think most people on this site are shooting for British English. You'll want to make sure you find books that emphasize the British.
Hope this Helps!