Youdon't have to worry about protein. I really don't see why so many people make a fuss of protein, but it's a macronutrient which is readilyavailable ina wide variety of foods. Considering that the amounts that the average person needs is approximately 50g, you really don't need to try to get protein.
Nutritionally speaking, the main concern for vegetarians, particularly vegans, is vitamin B12. However, the body stores it well, and you only reallyneed to be concerned if you've been vegetarian for a few years, when supplies will have depleted somewhat. I'v ebeen veggie for 9 years, and I've recently decided to start watching B12.
Iron is a bit of a problem if you're female, zinc if you're male, so you'd be best looking at these two micronutrients, and where to get them from, althoughin all honesty, I never bother checking myself.
Incidentally, the term "vegetarian" does not apply to people who eat fish. I'mnot being a purist or anything, but vegetarians don't eat fish, and I must admit that it is irritating, to say the least when people assume that I eat fish. It's doubly irritating when fish-based misconceptions extend to people involved in the catering industry.
As for resources, the first thing you need to do with the vegetarian society is ignore them. In my opinion, they are full of crap,and much of their campaign is based on "purity" and other crap. Plus, they really know sod all about public relations. The vegan society is much better. They have more info on nutrition on their website, and much of it translates to vegetarianism, although veganism is in essence, just a more strict form of vegetarianism.