Without being optimistic, it looks very unlikely that fault will come up tomorrow. Chances are morality will come up (virtually certain) but it's too risky learning just that.
I'm going to learn morality in a lot of detail, creativity in a good level of detail though apply my knowledge in the exam should it come up (I am familiar with a lot of it because of unit 1) and not really look at fault. I'll have a read over my notes and the textbook so that IF it does come up and the other 2 don't (which is second to none really), then I'll actually be able to produce some sort of answer.
Obviously there is a risk in not learning a particular essay, though realistically it isn't going to come up and I'd rather invest that time into revision elsewhere.
Chances are the essays will be morality, creativity and BCI. AQA didn't surprise us with unit 3 and I don't expect them to do so with this paper. A lot of people risked it and just revised NFOs which worked, though I wouldn't risk that for this one. Learning 2 is fine IMO, but just 1 is hedging your bets too much.