I'm using mint cinnamon edition . I'm not sure about short cuts,but have you tried right clicking the task bar ,click on settings ,click on applets . From the window that pops up you can select some applets that can help manage workspaces . I use 'work space switcher' applet, which adds big work space buttons  onto the task bar.
Not that I really need them ,as you said I can simply Ctrl+Alt+Arrow key to switch workspace.
Also you can add a 'thingy' << or that translates well :- onto the desk top ,so that for example if you hover your mouse pointer over it ,it brings up a display showing all the open work spaces including whats open on them .
Linux Mint Debian Edition- 64bit- Cinnamon (latest update)