It might depend from school to school, but at mine there were 3:
1. Half Yearly - was structured like Paper 1, Section 1 and 2 (creative writing) on Belonging, Section 3 on Mod C.
2. The trial examination - self explanatory
3. Externals - self explanatory
Since you only need to do creative writing in Paper 1 on the AoS, it's based on Belonging.
You can have a go at writing a creative piece or two. You probably haven't started learning Belonging yet, so it'll probably be a very limited/shallow exploration of the concept. My advice would be to have a look at the resources here on the BoS and examine how past students have explored Belonging in their creative writing, or if there are even just general notes on the concept of Belonging that will give you deeper understanding of the concept. Of course, avoid all clichés (remembering that clichés can also apply to descriptions, e.g. "a single tear glimmered down her cheek", "the second dragged on like a century", "and then he realised he belonged"). Realistically, you'll be refining the creative writing pieces during the year so don't worry too much about it. You probably won't even be tested on it until next year, so you'll have that huge 6 week holiday anyway