Sarah, I got a Tommee Tippee Formula Dispenser from Big W. You could probably get them at places like K-mart as well.

I put my formula in this and take a bottle of hot water with me and then make it up fresh when Jacob needs it. Alternatively, you can take cold water and then take something to heat the bottles up in yourself. I actually have something for this....it's kind of like a thermos, but not IYKWIM. I bought it from Target. You put boiling water in the thermos part, and then you screw the lid on, and then a cup fits down over the top of it and also screws on. When you need to heat a bottle, you simply pour the water from the thermos part into the cup and sit your bottle in it, just like you would do if you were heating a bottle in a jug of water at home. I often take this with me just in case the water I've already got in his bottle gets too cool. Alternatively, if the water is too hot, you can always just fill the cup up with cold water from a tap to cool the bottle down, so it's a very handy little gadget!!