You`ll almost certainly be able to find a gym.
Are you going with friends? Do press ups with them pushing on your back, or sitting on it, fill a bag with heavy objects, just use your head.
Fill a large bag with water bottles, its far from ideal, but you could do curls with it.
Have a look through this article http://www.muscletalk.co.uk/article-training-in-prison.aspx
I`d personally just stick to basic things, really high reps, with little or no rest.
Press ups, go slow down, throw yourself back up as fast as you can, superset it with flyes lying on the floor.
Shoulders, an OH press superset with front and side raises.
Legs, get as much weight into a backpack as you can, and just keep squating for as many reps as you can.
You`ll be able to find something to do pull ups on.
Lots and lots of tensing between sets to get the blood forced into your muscles, it makes a lot of difference.
Doing something is going to be far better than doing nothing at all.