You'll not get any protein in a zero calorie shake dude. By default a gram of protein is 4 calories. If you want a clean product then use a whey isolate, Bulk Powders do some nice flavours that mix well, their standard whey is nice also. Have it with water/Almond milk instead of cows milk if you want to keep your calorie intake low.
Thanks for the advice mate I'll have a look into that. Yeah I've just been getting all my protein from food for ages, eat a lot of tuna and chicken after lifting (not together) but it's a bit of a pain in the arse cooking and getting the meat off a roast chicken carcass on the reg. I don't think there's anything better about getting protein from a powder rather than from food but the inconvenience is getting to me.
What do you want to use it for? Any supplement is just that, it supplements your diet. If your diet is good and you are getting the correct amount of protein your body can't absorb anymore so it's just an expensive milkshake. My advice would be to get your diet right first then add a supplement if you are not getting enough protein from food. There have been many independent studies on protein powders and most show that they don't do much if anything at all for you unless you are an elite athlete or training like one. If you are training like that your diet needs to be correct. The only supplement that does make a difference to some people is creatine (it depends on your natural level) but be careful because, used too regularly, it has been linked with liver problems. It will also make you retain water, so it really depends on what you're training for. If it's to get ripped for the summer or to lose weight, this is not the supplement for you.
I'm getting it partly for convenience, so I don't have to eat so much protein all the time and partly in the hope that'll it'll help take me to the next level in terms of size. I know you can only absorb about 40 grams at any one time but several hours later you can take more on I believe. I'm already pretty big and me and the wife have a good diet but like anything when you're into it and been doing it a long time you want to keep on progressing.