To be honest there are no real differences between any of these expressions. You have used 'except,' and 'except for,' in your example above, both of which are correct. Had you used 'apart from,' or 'aside from,' those, too, would have been correct.
I think that the expression 'aside from,' is possibly more common in American English.
In general 'except,' is probably used most often. For example you will see 'except,' used on road signs, such as:
'No stopping, except for deliveries,' which means that drivers cannot stop in a particular road unless they are delivering supplies to a local business.