CAAP 234 says 45 mins. No variable.
The CAAPs are advisory only. They are not rules or regulations.
... all my ppl book says is you would be stupid not to include reserve fuel but not what the actual law is, nav book didn't mention it at all.
There are only two rules regarding fuel:
1. Thou shalt not run out of fuel. (CAR 234 (1988))
2. Thine Ops Manual shall contain directions as to how fuel load is to be calculated. (CAR 220 (1988)).
Being a simulated commercial operation,
wobblymammall, the exam material must have included a simulated Ops Manual, or, at the least, an extract of its fuel policy.
Yours may have been a private operation, but the Ops Manual must still give directions for this case.
In real commercial operations, it is possible that an operator's Ops Manual may explicitly reference that CAAP. This is the only way that that CAAP could be legally binding.