I found myself accidentally making changes in the wrong branch before I checked anything in. I tried to switch branch and it told me I couldn't because I had outstanding changes. I read that I could shelve changes, switch branch and then retrieve those changes on the correct branch.
I have done the first two steps but now can't find a way to actually unshelve the changes. I can't find anything in menus either in the toolbar or context menus. I've looked in the .hg/attic directory and I can see the changes stored there so I know that its not that they don't exist.