I like to use role plays in these situations, and try to make them a little trickier as they go on. You can start with, for example, going into a bank to open an account. One is the customer, one is the bank clerk. Once they have the basic vocab for this, the actual role play is pretty simple. However, having done it once or twice and having the students play each role, it's good to mix it up by perhaps telling the one playing the bank clerk that (s)he should now make life difficult for the other person. Perhaps insist that it's impossible to open an account with less than £1million! Or claim that unfortunately, there is a limit on how many people with dark hair can open an account in one day, and that limit has been reached. These kinds of exercises are great for helping the students be more creative and inventive, and they also usually turn out to be pretty funny into the bargain.
I also have an exercise which can help prepare them for being in noisy situations. I ask one student to hold a conversation with me, nothing complicated, simply a normal conversation on any topic. At the same time, I have the other student sit very close to us and read out loud from a passage. I also ask the other student to occasionally interrupt with a completely irrelevant question or statement. It's interesting to see if the one that you're trying to have the conversation with can continue to concentrate and manage to ignore the interruptions. You can test afterwards how well they managed by simply asking them to give a quick precis of the contents of the conversation (I sometimes find they remember more than I do!)