Re: What would you do?
Take mock as a real one. If you really do study and know your stuff, you will not forget it all (although it may feel like that but when you will revise for your finals you won't have to work so hard).
Basic philosphy is - more you revise more it stays in you head. More time you have more you can prepare. If you miss something or didn't preapred properly you will know with mock.