Hey Lucy, your location says Victoria. If you're in Melbourne, check out Savour Chocolate and Patisserie School in Brunswick, they always have transfer sheets in stock, but the size is probably not long enough to apply all the way around a cake, you'd need multiple strips. They also sell rolls of acetate strips which you could pipe designs directly on to. You'd have to be quick at piping to get the designs piped whilst the chocolate remained flexible enough to shape around the cake though.
I've seen chocolate applied to acetate and then whilst still semi-set applied directly around a cake, where it will shrink in and hug the cake, you just peel the acetate off after 20 minutes in the fridge if your chocolate is in temper. Alternatively, you could line the outside of the cake tin with baking paper, wait for the strip to be semi-set, wrap it around the cake tin + paper, let it set, slide it off, then carefully slide it over the cake (it should larger than the cake if you use the outside of the tin) but this way I think would be trickier depending on your decorations on the cake.
Do you know how to check your chocolate is in temper? I assume you've used the machine before if you have one 
Is it a melting tank or an actual tempering machine?
Edit to add: I definitely wouldn't use old camera film.
Chris (also in Victoria 
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