Can you run foremost without a LiveCD or LiveUSB? Because from what I have read (the Data Recovery page of Ubuntu), it says that you need one.
Sure you can, but since it works by reading a raw partition, you cannot use it to recover files from a mounted filesystem. That means that if you're trying to recover data from an external storage medium or an unmounted partition, it'll work. On the other hand, if you try to recover data from a mounted partition (e.g. one that is part of your running Ubuntu installation), you won't be able to reliable do so.
That brings you to a Live environment: all partitions are unmounted and you can safely perform read operations on a partition and write it to an external storage device.