I did the same thing when I had my community garden plot. I would chop kitchen scraps and put them in grocery store plastic bags in the freezer, then throw them in the back of the car when I went to the garden, which was about twice a week during the main season.

Now, if you are around a city, you need to be aware that kitchen scraps will likely attract rats, which are no more welcome in a community garden than they are around your house. What's more, as an infrequent visitor, you likely would never see the rats - but they would be there just the same. I had an elevated tumbler composter for that to keep the scraps away from rodents. So just beware, your fellow gardeners will not be pleased if your composting project turns in to rat heaven.

Not in the city, but we are pretty woodsy and do have wild life.