This is a feature we have on our todo list. We are planning on adding a roadblock option again. So this is on the todo list.
Are you referring to the navigation or the route planning? The navigation should work in landscape mode.
On most tablet the route planning should work in landscape as well.
It might be, that your tablet is recognized as a tablet by Android, given the resolution. If that is the case, please open a separate thread so we can discuss this.