Writing in exam

Concentrate on the latter, the same is situation with almost 80% of the students, one thing you should stick to is "communicate your idea to the examiner" don't worry about the length of your answers while doing so, quoting the correct section would be an icing on the cake.

All the best!!

draft the answer in your own language

If possible, use the tax language.. believe me if you really make the effort to remember the phrases, the technical terminology it will not only impress the examinor but also help you when you qualify.