Derrick Ha used a grand total of zero quotes in his essay compilation book as far as I can remember and he achieved a perfect 50. What you do need however are examples from the real world that demonstrate what you are trying to say in your essay, so don't think that just because you don't need quotes you don't need to do any external research to score well.
While quotes from profound linguists such as Kate Burridge, David Crystal and Don Watson can help augment your essays by demonstrating wider reading, they are in no way necessary if you can provide sufficient evidence to support your claims. I would also guess that a well-known and demonstrative example is much more conducive to a good mark than an obscure quote that the examiner knows the student could have just made up.
Also keep in mind that I believe the exam this year requires a direct reference to the stimulus material, so quoting elements of the stimulus as you address them may be helpful.