I haven't missed meat since I gave it up more-or-less on spur of the moment 8-9 years ago (long before ever hearing of Morrissey). I agree with Sister though, if you think it's going to be a challenge, don't tell yourself 'I will never eat meat again', instead be firm with yourself about not eating it for a specific amount of time, and you're almost guaranteed to feel better and want to stay off the meat.
Veggies will give you more vitamins, so no need to worry about that... I have always been a multivitamin-eater, though. My biggest sources of protein are:
-beans (especially pinto, black, and garbanzo)
-eggs or egg whites
-tofu
-soymilk
-natural peanut butter! and other nuts / nut butters
-some soy meat is really good - I recommend veggie buffalo wings from both Morningstar Farms and Health is Wealth
-whole grain breads and pastas; people often forget that wheat has good protein
I'm not especially big on milk, but if you are, it's a good protein source too of course. Some soymilks have just as much protein, too.
Good luck with it! Moz would be proud of you.
xo, math+